Following Kuo’s cumulus convection scheme,the contribution of cumulus convection to heating and humidifying a mesoscale convective complex(MCC)is investigated for itsrainfall efficiency,thereby estimating MCC precipitation, Results show that MCC rainfall calculation based on the developing stage is close to the reality both in quantity and distribution such that it serves to make estimation and prediction of MCCprecipitation for 6～12h in advance.