In this study, two heavy precipitation processes are simulated using the twomoment cloud microphysical scheme coupled with highresolution GRAPES model. The scheme is compared with WSM6 scheme, NCEP5 scheme and a variety of observation data to diagnose the prediction performance and analyze the key cloud microphysics process in deep convective precipitation. The simulation study shows that ice phase particles, especially graupel particles, play a leading role on the convection and precipitation in the deep convection clouds and the melting of graupel is the main source of heavy precipitation, while graupel distributes rarely in the stratiform precipitation region which is mainly affected by the melting of snow and warm cloud precipitation. The results derived from the twomoment scheme fit better with observations on rain belt direction, precipitation range and intensity. The scheme also has certain advantages on the maximum echo height and strength of convective cells, ice content distribution and cloud anvil structure. However, the ice content and echo height are slightly lower than observations. All these results would provide meaningful support for the improvement and operational application of the twomoment scheme.