Facing the challenge of extreme measurement conditions such as short time and high speed, the photonic Doppler velocimetry (PDV) system develops rapidly in four aspects: larger dynamic range, higher sensitivity, higher temporal resolution and multi-channel measurement ability. Firstly, the principle and background of photonic Doppler velocimetry is introduced in detail. Secondly, the classical improvement methods and development status of transient high-speed PDV system with measuring speed above 100m/s and recording time of nanoseconds are classified and summarized. Then, the application of time stretches and time lens in the PDV system is emphatically introduced, and the characteristics and potential of time amplification are discussed. Finally, the problems of the transient high speed PDV system are summarized and its future development is prospected.