面向远距离目标微多普勒效应的探测，建立了本振光功率变化对激光平衡外差探测回波信噪比影响的数学模型，并进行了仿真分析。通过搭建的1 550 nm激光平衡外差探测实验平台测试了由于本振功率变化对于目标微多普勒特征提取效果的影响。研究结果表明，对于平衡外差探测，由于两光电探测器量子效率不可能完全匹配，考虑到散粒噪声、热噪声和本振相对强度噪声的影响，将存在一个最佳本振功率值使探测信噪比达到最大。当选取该本振功率进行探测时，获得的目标微多普勒特征可读性更强，提取误差更小。

Aimming at detecting the micro-Doppler effect of target away, the mathetical model of variational Local Oscillate (LO) power influence to signal to noise ratio(SNR) of balanced heterodyne detection for coherent lidar were established. Besides, simulation analysis on this model was proceeded. The effect on feature extraction was observed through experiments. The results show that in balanced heterodyne detection, where quantum efficiency of two photo electric detectors can′t match completely in reality, there will be a specific LO power making the SNR best, considering the shot noise,hot noise and LO intensity noise. While choosing the optimal LO power in detection, the micro-doppler feature extracted will be more readable and accurate.