Abstract: By using the data of rice Planthopper of Jiangsu and weather background(stream and temperature field on 700hPa and 850hPa),the low level circumfluence characteristic during immigration peaks was analyzed in Jiangsu 2007.The average circumfluence background and wind velocity distribution that lead to rice planthopper rapid increasing were discussed.The results showed that there were two kinds of circumfluence to arise Jiangsu rice planthopper rapid increasing in 2007.Firstly,there was obvious southwest low level jet due to southwest warm-humidity air stream.Secondly,there was northeast stream by the tropic cyclone moving to north or west.The range of southwest airflow(gale area) in 700hPa and 850hPa took on well showing meaning to rice planthopper area.There was some relation between the gale range in 850hPa of tropical cyclone and back immigration of planthopper in 2007.The results provided references to forecast the rapid increasing time,influence area and back immigration condition.

Key words: Rice planthopper(white-backed planthoppe and black planthoppe), Immigration peaks in certain time, Low level circumfluence, Coupling analysis