Traditional PN code acquisition algorithm is effectless for high dynamic Doppler shift signals.This paper presents acquisition methods based on FFT . It considers Doppler frequency change rate in high dynamic environment and improves the model of the received signal. It divides traditional twodimensional search algorithm into the separate estimation of Doppler frequency offset and frequency change rate as well as pseudocode phase. The complexity and signaltonoise ratio of Doppler frequency shift estimation method, Matching Fourier Transform and Delay Selfcorrelation, and code phase circular correlation estimation method are analysed and improved. The simulation by using MATLAB verifies that the algorithm is correct and effective.