Two cases of heavy rainfall occurred in Jilin Province in July, 1991 are diagnosed and simulated by using MM2 and MM4 mesoscale models. The results of diagnostic analyses show that the case of 20th July is a mesoscale cumulus complex (MCC) developed in warm area. The vertical profile of the apparent heat source (Q1) for this heavy rain from the only cumulus cloud has two peaks. However, for case 21th to 22th July, MCCs embody in stable precipitation of cyclone with only one peak of Q1 apparent heat source vertical profile. This single peak is over about 550 hPa and is lower than the upper peak of the former case. The results from numerical simulation indicate that the heights of cumulus heating peaks for different weather systems are different and, this different of heating peak heights may cause different feedback to large scale environmental field.