Numerical experiments on four cumulus parameterization schemes (CPSs) are carried out using the data of a Meiyu heavy rainstorm event occurred over the Changjiang basin in July 2002 with MM5 model. The impacts of different CPSs under the same model horizontal resolutions on rainfall, the mesoscale feature,and the microphysics feature of clouds are discussed. The results indicated that different CPSs have significantly different effects on rainfall intensity, but a little on the location of the rainfall center. The contributions to the total precipitation of four schemes are obviously different. The GR and KF schemes, which include subgrid scale moist downdrafts, are able to reproduce mesoαscale vortex features. The simulated cloud physical characteristics using four CPSs show significant difference.