MMW Chirp - SF radar is a kind of radar to get high range resolution, but the problem of rangevelocity coupling is serious. So it is necessary to carry out the motion compensation in order to increase the range resolution of moving target. This paper puts forward a velocity measurement method compounding the Pulse Doppler velocity measurement and the time-domain correlation method based on Chirp - SF signal. The simulations results show that this method can be used to measure velocity accurately with simple arithmetic and high speed.