The invention relates to a dynamic rail transit vehicle speed measurement method. According to different sampling frequencies and the current speed frequency value, a segmental frequency and the number of spacing pulses are adjusted adaptively, the number of pulses in the sampling period is dynamically adjusted according to the speed of the vehicle, and further, the vehicle speed can be measured dynamically. The method of the invention uses the high-speed operation rate of an FPGA and precise timing for realization, the contradiction between the sampling precision and the real-time performance during a dynamic speed measurement process can be well solved, and signal filtering processing can effectively suppress speed pulsation caused by the precision of a speed measuring gear.