According to the measurement of wheel profile by line test for high speed train, the contact geometry of new and worn wheel profiles S1002GCN with different wear mileages are studied .The relationship between contact angle difference and equivalent conicity of wheel/rail contact is analyzed, which provide a basis for stability study when wear profiles are difficulty to obtain. A high speed dynamic model is established and the stability of vehicle is analyzed with the new and the worn wheel profiles respectively. The results showed that: the relationship between the equivalent conicity and contact angle tend to a constant with wheel wear. Equivalent conicity, the longitudinal stiffness of the primary suspension affect the amplitude and the form of bifurcation. From the simulation results we can see that rail cant, track gauge and rail grinding have nonlinear relationship with the contact geometry between the worn wheel profile and rail.