As the core element of a 532 nm Doppler lidar, Fabry-Perot etalon has direct effects on the velocity sensitivity and measurement precision. The reason of selecting 532 nm as the laser wavelength was analyzed by simulating the received signal. Optimizations of the free spectral range, full width at half maximum and peak value interval in three channels were presented by analyzing the velocity sensitivity and relative error. 9 GHz is selected as the free spectral range, and 1.75 GHz as the full width at half maximum, 4 GHz and 1.125 GHz as the interval between two edge channels and between the edge channel and locking channel respectively. The precision during processing and parallelism adjusting during experiment of the etalon was analyzed by simulating effects on the transmission of the main defects. 5 nm of processing precision and 10 nm of the maximal difference of the etalon spacing are required in the system.