Mukesh,
You could use the TS_PropertyGetType() function in CVI to do this. Here is a reference page for the GetType function--you can see that it returns a PropertyValueType which will indicate which type the PropertyObject (variable) is. In CVI, you'll find this function in the NI TestStand API 2013 instrument methods, under PropertyObject > Static Properties.
Hope it helps, and let us know if you have any more questions about it!