diff --git a/src/components/AssignmentBoard.tsx b/src/components/AssignmentBoard.tsx
index c2ce526b..1b1723ce 100644
--- a/src/components/AssignmentBoard.tsx
+++ b/src/components/AssignmentBoard.tsx
@@ -66,8 +66,8 @@ const AssignmentBoard: FunctionComponent<
         ext
       });
     } else {
-      showToast("文件下载中……", 3000);
-      const success = await shareFile(url, ext);
+      showToast("文件下载中……", 1000);
+      const success = await shareFile(url, filename, ext);
       if (!success) {
         showToast("文件下载失败", 3000);
       }
diff --git a/src/components/NoticeBoard.tsx b/src/components/NoticeBoard.tsx
index de8f3b78..f29254c4 100644
--- a/src/components/NoticeBoard.tsx
+++ b/src/components/NoticeBoard.tsx
@@ -56,8 +56,8 @@ const NoticeBoard: FunctionComponent<
         ext
       });
     } else {
-      showToast("文件下载中……", 3000);
-      const success = await shareFile(url, ext);
+      showToast("文件下载中……", 1000);
+      const success = await shareFile(url, filename, ext);
       if (!success) {
         showToast("文件下载失败", 3000);
       }
diff --git a/src/helpers/share.ts b/src/helpers/share.ts
index 0bcf7be5..39b12fa9 100644
--- a/src/helpers/share.ts
+++ b/src/helpers/share.ts
@@ -1,3 +1,4 @@
+import { Platform } from "react-native";
 import Share from "react-native-share";
 import RNFetchBlob from "rn-fetch-blob";
 
@@ -22,30 +23,52 @@ export const mimeTypes: any = {
   rar: "application/x-rar-compressed"
 };
 
-export const shareFile = (url: string, ext: string) => {
+export const shareFile = (url: string, name: string, ext: string) => {
   return new Promise<boolean>(async (resolve, reject) => {
     if (!supportedFileTypes.includes(ext.toLowerCase())) {
       reject("Unsupported file type");
     }
 
-    const res = await RNFetchBlob.fetch("GET", url);
-    const status = res.respInfo.status;
+    const filePath = await downloadFile(url, name, ext).catch(() =>
+      reject("Download failed")
+    );
 
-    if (status !== 200) {
-      reject();
-    } else {
-      const base64Str = res.base64();
+    if (filePath) {
       Share.open({
-        url: `data:${mimeTypes[ext]};base64,${base64Str}`,
+        url: Platform.OS === "android" ? "file://" + filePath : filePath,
         type: mimeTypes[ext],
         title: "打开文件",
         showAppsToView: true
       });
+
       resolve(true);
     }
   });
 };
 
+export const downloadFile = (url: string, name: string, ext: string) => {
+  return new Promise<string>(async (resolve, reject) => {
+    const dirs = RNFetchBlob.fs.dirs;
+    const filePath = `${dirs.DocumentDir}/files/${name}.${ext}`;
+    const exists = await RNFetchBlob.fs.exists(filePath);
+
+    if (!exists) {
+      const res = await RNFetchBlob.config({
+        fileCache: true,
+        path: filePath
+      }).fetch("GET", url);
+      const status = res.respInfo.status;
+      if (status !== 200) {
+        reject();
+      } else {
+        resolve(res.path());
+      }
+    } else {
+      resolve(filePath);
+    }
+  });
+};
+
 export const getExtension = (filename: string) => {
   return filename.split(".").pop();
 };
diff --git a/src/screens/CourseDetailScreen.tsx b/src/screens/CourseDetailScreen.tsx
index 879c2b66..ccea97b4 100644
--- a/src/screens/CourseDetailScreen.tsx
+++ b/src/screens/CourseDetailScreen.tsx
@@ -128,8 +128,8 @@ const CourseDetailScreen: INavigationScreen<
         ext
       });
     } else {
-      showToast("文件下载中……", 3000);
-      const success = await shareFile(url, ext);
+      showToast("文件下载中……", 1000);
+      const success = await shareFile(url, filename, ext);
       if (!success) {
         showToast("文件下载失败", 3000);
       }
diff --git a/src/screens/FilesScreen.tsx b/src/screens/FilesScreen.tsx
index 7e6a2f17..cfcdeff2 100644
--- a/src/screens/FilesScreen.tsx
+++ b/src/screens/FilesScreen.tsx
@@ -115,8 +115,8 @@ const FilesScreen: INavigationScreen<IFilesScreenProps> = props => {
         ext
       });
     } else {
-      showToast("文件下载中……", 3000);
-      const success = await shareFile(url, ext);
+      showToast("文件下载中……", 1000);
+      const success = await shareFile(url, filename, ext);
       if (!success) {
         showToast("文件下载失败", 3000);
       }
diff --git a/src/screens/SettingsScreen.tsx b/src/screens/SettingsScreen.tsx
index 7692543a..1aa55356 100644
--- a/src/screens/SettingsScreen.tsx
+++ b/src/screens/SettingsScreen.tsx
@@ -12,6 +12,7 @@ import { iOSColors } from "react-native-typography";
 import MaterialCommunityIcons from "react-native-vector-icons/MaterialCommunityIcons";
 import MaterialIcons from "react-native-vector-icons/MaterialIcons";
 import { connect } from "react-redux";
+import RNFetchBlob from "rn-fetch-blob";
 import packageConfig from "../../package.json";
 import Divider from "../components/Divider";
 import SettingsListItem from "../components/SettingsListItem";
@@ -135,6 +136,29 @@ const SettingsScreen: INavigationScreen<ISettingsScreenProps> = props => {
     }
   };
 
+  const onClearFileCachePress = () => {
+    Alert.alert(
+      "清空文件缓存",
+      "确定要清空文件缓存吗？",
+      [
+        {
+          text: "取消",
+          style: "cancel"
+        },
+        {
+          text: "确定",
+          onPress: async () => {
+            await RNFetchBlob.fs.unlink(
+              `${RNFetchBlob.fs.dirs.DocumentDir}/files`
+            );
+            showToast("成功清空文件缓存", 1500);
+          }
+        }
+      ],
+      { cancelable: true }
+    );
+  };
+
   const renderListItem: ListRenderItem<{}> = ({ index }) => {
     switch (index) {
       case 0:
@@ -169,6 +193,15 @@ const SettingsScreen: INavigationScreen<ISettingsScreenProps> = props => {
           />
         );
       case 3:
+        return (
+          <SettingsListItem
+            variant="none"
+            icon={<MaterialCommunityIcons name="file-hidden" size={20} />}
+            text="清空文件缓存"
+            onPress={onClearFileCachePress}
+          />
+        );
+      case 4:
         return Platform.OS === "android" ? (
           <SettingsListItem
             variant="none"
@@ -197,7 +230,7 @@ const SettingsScreen: INavigationScreen<ISettingsScreenProps> = props => {
             onPress={onCheckUpdatePress}
           />
         ) : null;
-      case 4:
+      case 5:
         return (
           <SettingsListItem
             variant="arrow"
@@ -207,7 +240,7 @@ const SettingsScreen: INavigationScreen<ISettingsScreenProps> = props => {
             onPress={onAcknowledgementsPress}
           />
         );
-      case 5:
+      case 6:
         return (
           <SettingsListItem
             variant="arrow"
@@ -228,6 +261,7 @@ const SettingsScreen: INavigationScreen<ISettingsScreenProps> = props => {
           { key: "autoRefreshing" },
           { key: "calendarSync" },
           { key: "logout" },
+          { key: "clearFileCache" },
           { key: "checkUpdate" },
           { key: "acknowledgement" },
           { key: "about" }
diff --git a/src/screens/WebViewScreen.tsx b/src/screens/WebViewScreen.tsx
index b4df959e..587142e4 100644
--- a/src/screens/WebViewScreen.tsx
+++ b/src/screens/WebViewScreen.tsx
@@ -1,31 +1,41 @@
-import React, { useState } from "react";
+import React, { useEffect, useState } from "react";
 import { View } from "react-native";
 import Icon from "react-native-vector-icons/MaterialIcons";
 import { WebView } from "react-native-webview";
 import MediumPlaceholder from "../components/MediumPlaceholder";
-import { shareFile } from "../helpers/share";
+import { downloadFile, shareFile } from "../helpers/share";
 import { showToast } from "../redux/actions/toast";
 import { store } from "../redux/store";
 import { INavigationScreen } from "../types/NavigationScreen";
 
-export interface IWebViewScreenProps {
-  readonly url: string;
-}
-
-const WebViewScreen: INavigationScreen<IWebViewScreenProps> = props => {
+const WebViewScreen: INavigationScreen<{}> = props => {
   const url = props.navigation.getParam("url");
+  const name = props.navigation.getParam("filename");
+  const ext = props.navigation.getParam("ext");
 
   const [loading, setLoading] = useState(true);
+  const [filePath, setFilePath] = useState("");
+
+  useEffect(() => {
+    if (loading) {
+      (async () => {
+        const filePath = await downloadFile(url, name, ext);
+        if (filePath) {
+          setFilePath(filePath);
+          setLoading(false);
+        }
+      })();
+    }
+  }, [loading]);
 
   return (
     <>
       <WebView
         source={{
-          uri: url
+          uri: filePath
         }}
         useWebKit={false}
-        // tslint:disable-next-line: jsx-no-lambda
-        onLoadEnd={() => setLoading(false)}
+        originWhitelist={["*"]}
       />
       {loading && (
         <View
@@ -58,7 +68,11 @@ WebViewScreen.navigationOptions = ({ navigation }) => {
         // tslint:disable-next-line: jsx-no-lambda
         onPress={() => {
           store.dispatch(showToast("准备文件中……", 1500));
-          shareFile(navigation.getParam("url"), navigation.getParam("ext"));
+          shareFile(
+            navigation.getParam("url"),
+            navigation.getParam("filename"),
+            navigation.getParam("ext")
+          );
         }}
         color="white"
         size={24}