In order to detect and recognize remote targets based on micro-Doppler effect，the influence of heterodyne lidar system composed by acousto-optic frequency shifters to micro-Doppler feature extraction is researched. Mathematical models between driving power of frequency shifter and signal to noise ratio are established, and simulations and experiments are performed through 1550 nm experimental system to verify their validity. The research shows that within the limiting driving voltage scope, the higher the voltage, the better the detection result is, which is in accordance with the theoretical analysis. Through the contrast experiment，heterodyne detection system is found better than homodyne in time-frequency curve of target feature acquisition. The smaller extracting error and the higher readability indicate that heterodyne system is more conductive than complicated remote target detection.