A heavy torrential rainfall process during August 17 and 18,2009 is analyzed by using both normal and abnormal data such as radar data.The results show that:1) the torrential rainfall mainly occurred in the border district of northwest subtropical high when the trough moved eastward and the subtropical high moved backward to the south;2) some thermal environmental indexes like CAPE presented good corresponding relationship with intensive rainfalls in south Shandong province;3)distribution of precipitation was profoundly affected by the topographic condition;the complex topography of mountains in Shandong Province can lead to significant precipitation amplification and block the movement of the convective systems;4) low jet stream and train effects existed in the torrential rainfall;the strong radarecho lasting for a long time is the main reason for the heavy rain in Feixian;the strong southerly flow and the thick moist air are the leading factors for the torrential rainfall;5) the theory of the impact of terrain on precipitation well explains the distribution of precipitation in this torrential rainfall progress;6) the special terrain of Feixian contributes to the heavy rainfall greatly.Radar data is a good supplement to normal observational data.The impact of terrain exerts important influence on strong precipitation and its distribution.