Abstract: In order to realize the extraction of vibration features at 100 Hz from a distance of 4 km, a method of using laser micro-Doppler to enhance the capacity of missile target identification was proposed, and a laser transmitting/receiving/video common aperture system based on polarization splitting was designed.This compact two-stage stable system is adapted to the missile-borne environment, and the optical path is compensated automatically by optical fiber selection, the coherent light matching can be realized. Using the coherence method of local oscillator/echo signal, the detection pulse light is formed by the modulation of local oscillator light with a line width of 300 Hz, so the detection range can be improved, also the false peak caused by the attenuation of atmosphere can be avoided. The Fourier transform circuit constructed by FPGA/DSP can obtain the time-frequency curve signal, the identification of the target can be achieved when the frequency is 36 kHz.