The improved capture method combined by matched filter and FFT is introduced, aiming at the frequency range of GPS LIC signal. This method effectively combines the advantages of serial capture and parallel acquisition, which can decrease the hardware resources and realize the rapid capture of the signals, PN code acquisition simulation and algorithm analyses can be realized on the platform of MATLAB. Hardware implementation and time sequence simulation can be done by FPGA. This method can increase the anti-interference of the navigation system in the complex environment, supply the reference for the PN code acquisition in the special environment and it can be used in the receiving platform design of the new-type navigation signals.