We discussed the reasons of‘8．30’storm rainfall caused by typhoon 0012 bas ed on the upper circulative characters during the course of heavy rain, the evol vement of hour-to-hour satellite cloud picture and the analysis of single statio n meteorological elements of the maximum hour-to-hour storm rainfall center. It was shown that for the precipitation processes ,including the first and second s trong preci pitation phases, the major cause of this rare storm rainfall was the result of interaction among the typhoon circ ulation, western jet and the cold trough (frontal zone),and the third precipitat ion phase was affected by typhoon itself.