The Morrison's double-moment microphysics scheme is incorporated into the mesoscale model WRF V2.2 to simulate the weather process of snow and rain from 00:00 UTC 25 to 12:00 UTC 29 January 2008 in the southern China.Based on the correct simulation of the weather evolvement,the sensitivity experiments are used to research the impact of cloud droplet number concentration on accumulated precipitation in the microphysics schemes,showing that the impact is complicated and nonlinear.The microphysics properties in the weather process are analyzed in detail.The evolution of each hydrometeor class is analyzed to find out the effect of cloud droplet number concentration increase on the warm cloud and cold cloud precipitation processes.Results indicate that the higher cloud droplet number concentration is,the higher cloud water mixing ratio is,and the smaller cloud droplet size is.In addition,the response of rain droplet to cloud droplet number concentration is opposite to the response of cloud droplet.The higher cloud droplet number concentration is,the lower rain droplet number concentration is,and the lower rain water mixing ratio is,which leads to the warm cloud precipitation to be inhibited.Because of the increase of cloud droplet number concentration,the number concentration of ice crystal and snow have no obvious change.However,the mixing ratio of ice crystal and snow becomes higher as the cloud droplet number concentration increases,so the cold cloud precipitation is enhanced.This case is simulated by using different cloud droplet number concentration,the difference of total precipitations is less than 1%.In general,the precipitation decreases when the cloud droplet number concentration increases.The proportion of decrease of warm cloud precipitation is much higher than that of increase of cold cloud precipitation.However,in this case,the dominant process is cold cloud precipitation.The absolute values of decreased and increased precipitations are similar and of the same order of magnitude.The result of their counteraction is that the value of total simulated precipitation has no obvious change when the cloud droplet concentration increases.