Abstract: The traditional lidar usually uses Doppler effect to obtain the radial velocity of the target, but it is difficult to achieve this function when the echo signal is as low as single photon level. In this paper, we explore a method of velocity measurement using time-correlated single photon counting (TCSPC) technology. We have built a high repetition rate and high precision TCSPC velocity measurement system and carried out experimental research. The results show that the velocity measurement error is directly related to the photon count for single ranging under a certain velocity measurement duration, and the velocity measurement error is optimal when the photon count for single ranging is 1000-5000 under the experimental conditions in this paper. This method is expected to replace the Doppler velocity measurement method in the future and realize the velocity measurement of long-distance and high-speed moving targets.