Abstract: Rice planthopper unusual occurred in Sichuan province in 2012, the occurrence characteristics liked the first immigration peak emerged early, the times of immigration peaks and the number of rice planthopper are both more than usually years. Anaylysed the reason of this unusual occurrence can draw a conclusion as follow: The base number of rice planthopper in oversea and Guangxi province were huge. At the same time, the climate of Sichuan province in 2012 was so suitable for rice planthopper to immigrate and propagate.