With the conventional and intensive observation data and FY-2 satellite products, the mesoscale convective systems (MCSs) that caused th e “7.18" severe heavy rain over Jinan are analyzed. The mesoscale convergence center and line played important roles. Furthermore, the severe heavy rain occurr ed near the center of mesoscale low pressure and accompanied with them. The ne w cloud clusters which generated behind the right rear of the weakened clouds dev eloped from mesoγ to mesoβ scale. Under enough vapor conditions, they expa nded into compacted αscale clouds with a clear edge that directly caused the se vere heavy rain. The maximum precipitation was strongly related to the lowest TBB measured by FY2 satellite, therefore, FY-2 satellite products is very impor tant in nowcasting.