Abstract: Based on the precipitation data and radar echo data from March to October during 2004-2009, 45 heavy rain events were analyzed in order to improve the warning ability to heavy rain. The results indicated that there are 32 short time heavy rain events. Among them, 27 events occur in July and August that accounts for 84.4% of the whole. The mixed precipitation echoes between sever convection and stability along the coast of southwestern, southern and southeastern Dalian are the main reasons causing the short time heavy rain and account for more than 70%. A further study is conducted by using town-level precipitation data from AWS and radar echo data. It finds that the direct cause of short time heavy rain in Dalian is the instantaneously generated mixed meso-β echoes. Thus, the mixed meso-β echoes model is set up. This model could improve early warning ability of short time heavy rain with other methods.