Abstract:Using Jianghuai cyclone data obtained from Lu (2017) improved method of identifying and tracking of extratropical cyclone, this paper statistically analyzed the overview, path, circulation characteristics and corresponding rainstorm distribution of Jianghuai cyclone which brought the regional heavy rain of Jiangsu in summer in recent 40 years. The results show that most heavy rains in Jiangsu Province located between Yangtze River and Huaihe River are caused by Jianghuai cyclone in summer. The heavy rain caused by the summer Jianghuai cyclone is the most in June, accounting for about 1/3 of total number of heavy rains in this month. The rainstorm areas caused by Jianghuai cyclone are related to the path of cyclone, especially in the areas of north of Yangtze River where the heavy rains are evenly distributed on both sides of the cyclone path. However, heavy rain is mainly concentrated in the western and central sections of the cyclone path in south of Yangtze River. The circulation conditions causing heavy rain by Jianghuai cyclone can be divided into two types, which are the westward flow and the low trough patterns. The number of low trough pattern appears to be about twice of westward flow pattern. The heavy rain area is located in the transitional zone between warm and humid southwest airflow and northwest airflow at 500 hPa in the westward flow pattern and the heavy rain area of low trough pattern is located in southwest flow ahead of the trough. The two types of 850 hPa circulation conditions are similar basically, both of which are closed vortices, and the vortex position is obviously southward compared with 700 hPa. Most of heavy rain areas are located in the south side of 700 hPa and 850 hPa vortex centers and the north of 700 hPa and 850 hPa jet in south of Huaihe River. The areas of heavy rain caused by westward flow and low trough pattern are same, but the rain caused by low trough pattern is heavier than that of westward flow pattern.