Abstract: Based on the existing cumulus parameterization schemes, a Mass Flux Scheme for cumulus convective parameterization, i.e. MFS, has been successfully developed by referenced the work of Chen Bomin. MFS is a comprehensive scheme. In MFS, notonly the importance of the large-scale moisture convergence is taken into acxeount, but also itincludes the cumulus updrafts, cumulus downdrafts, cumulus induced subsidence in the environmental air, entrainment, detrainmentand evaporation. The interaction between the cumulus and the environmentis described by using a one-dimensional bulk model. Atthe same time the scheme includes the penetrative and shallow convection.The MFS has been successfully imported into the regional climate model RegCM2 developed by NCAR.The new model has been applied to simulate summer monsoon characteristics and their variations of heavy rainfall process in the Changjiang-Huaihe River Basin for three months from May to July 1991.The results show that the new model can successfully simulate this rainfall process.By comparison the model out puts of RegCM2 using the Kuo scheme and the MFS,it is found that the MFS is betterin the surface temperature,rainfall area,rainfall period of time and the intermission simulation.