diff --git a/seispy/ccppara.py b/seispy/ccppara.py
index ca3d869..b58faa6 100644
--- a/seispy/ccppara.py
+++ b/seispy/ccppara.py
@@ -15,7 +15,7 @@ def __init__(self):
         self.stalist = 'sta.lst'
         self.peakfile = 'good_410_660.dat'
         self.adaptive= False
-        self.velmod = ''
+        self.velmod = 'iasp91'
         self.stack_sta_list = ''
         self.domperiod = 5
         self.shape = 'circle'
@@ -59,6 +59,19 @@ def shape(self, value):
         else:
             self._shape = value.lower()
 
+    @property
+    def velmod(self):
+        return self._velmod
+
+    @velmod.setter
+    def velmod(self, value):
+        if not isinstance(value, str):
+            raise TypeError('ccppara.velmod must be str type')
+        elif value == "":
+            self._velmod = 'iasp91'
+        else:
+            self._velmod = value
+
 
 def ccppara(cfg_file):
     """ Read configure file for CCP stacking
diff --git a/seispy/rf2depth_makedata.py b/seispy/rf2depth_makedata.py
index 209534c..2dde17c 100644
--- a/seispy/rf2depth_makedata.py
+++ b/seispy/rf2depth_makedata.py
@@ -153,7 +153,6 @@ def makedata(self, psphase=1):
             if self.ismod1d:
                 if self.modfolder1d is not None:
                     velmod = _load_mod(self.modfolder1d, _sta.station)
-
                 else:
                     velmod = self.cpara.velmod
 
@@ -169,12 +168,17 @@ def makedata(self, psphase=1):
             else:
                 ### 3d model interp
                 if self.raytracing3d:
-                    pplat_s, pplon_s, pplat_p, pplon_p, newtpds = psrf_3D_raytracing(stadatar, self.cpara.depth_axis, self.mod3d, srayp=self.srayp, sphere=sphere)
+                    pplat_s, pplon_s, pplat_p, pplon_p, newtpds = psrf_3D_raytracing(
+                        stadatar, self.cpara.depth_axis, self.mod3d, srayp=self.srayp, sphere=sphere
+                    )
                 else:
                     pplat_s, pplon_s, pplat_p, pplon_p, raylength_s, raylength_p, tps = psrf_1D_raytracing(
-                        stadatar, self.cpara.depth_axis, srayp=self.srayp, sphere=sphere, phase=psphase)
-                    newtpds = psrf_3D_migration(pplat_s, pplon_s, pplat_p, pplon_p, raylength_s, raylength_p,
-                                                tps, self.cpara.depth_axis, self.mod3d)
+                        stadatar, self.cpara.depth_axis, velmod=self.cpara.velmod, srayp=self.srayp, sphere=sphere, phase=psphase
+                    )
+                    newtpds = psrf_3D_migration(
+                        pplat_s, pplon_s, pplat_p, pplon_p, raylength_s, raylength_p,
+                        tps, self.cpara.depth_axis, self.mod3d
+                    )
                 if stadatar.prime_phase == 'P':
                     piercelat, piercelon = pplat_s, pplon_s
                 else:
diff --git a/setup.py b/setup.py
index 0e91e5b..746c82d 100644
--- a/setup.py
+++ b/setup.py
@@ -6,7 +6,7 @@
     long_description = fh.read()
 
 
-VERSION = "1.3.8"
+VERSION = "1.3.9"
 setup(name='python-seispy',
       version=VERSION,
       author='Mijian Xu',