We discuss the methods to apply pulse integration in coherent lidar, and simulate the course of signal processing by Simulink softplat. According to the result of the simulation, under certain parameters set, signal-noise ratio (SNR) can achieve 22 dB at least, when the coherent integrated time is more than 0.028 s. If we process a shot-time coherent integration within 0.007 s at first, then process non-coherent integration, SNR can achieve 18 dB at least, when the total integrated time is more than 0.020 s.