Abstract: A multi-size convective storm occurring in Aksu region in Xinjiang, Northwest China was simulated using the Weather Research and Forecasting (WRF) mesoscale model, which includes the parameterization for the concentration of ice nuclei proposed by DeMott et al. (2010). Sensitivity tests have been conducted and results were compared under different background conditions to investigate the response of cloud microphysical processes and precipitation to changes in concentrations of ice nuclei. It is found that the increase in concentrations of ice nuclei under the background aerosol condition and dust condition has little influence on rainfall rate in central area of the rain region, but has a significant influence on the regional distribution of the rainfall. The mass and number concentrations of ice crystal and snow particle increase obviously with the increase in the concentration of ice nuclei under different conditions. The main source of snow growth is the deposition of snow. The main source of graupel growth is the collection of supercooling cloud droplets by ice phase particles. When the concentration of ice nuclei increases in the background aerosol condition and dust condition, the number concentration of graupel increases but the graupel size decreases.