Abstract: The acquisition model of partial matched filter combined with FFT is used in the acquisition of navigation signals in high dynamic environment. Because of its high tolerance to the Doppler frequency error, it can do parallel search in frequency domain, which reduces the acquisition time and enables the whole system to have a high detection probability. This paper analyses the principle of the PMFFFT acquisition algorithm and the loss of each part in the acquisition process in detail by establishing the mathematic model, and then comes up with an improved acquisition method according to the aperiodic characteristics of the Pcode. The overlapandsave method is applied to achieve time domain parallel search in the frequency domain. Through this method, the acquisition time can be further reduced. Finally, according to the principle of the minimum total operation time when reaching the equivalent signaltonoise ratio, some guidance to the optimum design of the parameters in the algorithm is given, which has a certain reference.