Abstract: Diagnostic analysis on a local extra heavy rain event occurred in central Shandong province on 3 July 2011 was made by using conventional meteorological data, FY-2E satellite TBB data, the intensive observations of automatic weather stations and NCEP reanalysis data.The results show that this event occurs under the synoptic situation and its precipitation process presents the characteristics of strong mesoscale convective system (MCS). The distribution of severe precipitation locates in the convergence center in wind field ahead of the cold front observed from the ground automatic weather station, and both MαCS and MβCS are synoptic systems which influenced the event directly.The severe precipitation emerges in the period from remarkable development to mature stage of MCS, and distribution of rain is initially in the greatest gradient areas of TBB and then moves down to leeward along the areas mentioned above, and locates all along in rear of strong cold cloud top region. From high latitudes the northeast airflow wedging into the low-level over heavy rain areas has an important triggering effect on precipitation. Corresponding with isoneph dense areas in steep plane of pseudo-equivalent potential temperature, the severe precipitation zone locates on south of shear line in the low-level and in the isoneph dense zones on the left of high vapor flux tongue zone.