Based on the measurement of train speed, this paper briefly describes the basic principle of Doppler speed measurement and the design of speed measurement system. By the analysis of test signal which simulates the actual speed signal and comparison of the simulation results, the AR power spectrum estimation algorithm is selected as the model of speed measurement system, and the Burg method is selected to evaluate the Doppler frequency. Then the effect of parameters such as sampling frequency, length of the input vector, FFT length and estimation order on power spectrum estimation are analyzed, the optimization principles of the parameters are defined. Finally, the determined method is simulated with a high-noise, multi-jamming signal and has good results. The accuracy, stability and immunity are proved by the simulation.