Abstract: Vertical air motions have a big impact on the retrieval of raindrop size distribution (DSD) by Precipitation Doppler radar. The method of average final velocity is applied to calculate speed of vertical air motions and DSD. On surface DSD comparison observations, the DSD retrieved by Precipitation Doppler radar is more reasonable after the influence of vertical air motions is eliminated, better at Parsivel DSD’s consistency, and the average relative error is reduced by 8%. The effect is very obvious on rain rate, the average relative error is reduced by 25% in heavy rain rate. It is shown that the method of average final velocity has a certain reference value.