Abstract: Using NCEP reanalyzed data of 850hPa and rainfall data in Guangdong, the variations of rainfall anomalies in Guangdong associated with summer monsoon are investigated by correlation analysis and composite and contrast methods. The significant correlation between the rainfall and southwest winds over the north part of South China Sea(NPSCS)has been found. In the first stage of rain period in Guangdong(April to June), the summer monsoon can bring precipitation to Guangdong, but the relationship between the rainfall anomaly and the intensity of summer monsoon is not significant. The anomalously more rainfall in Guangdong happens in the period of the weaker tropical monsoon and strong subtropical monsoon during May and June. In the second stage of rain period(July to September), the rainfall is greater with stronger southwest monsoon in NPSCS and weaker subtropical southeast monsoon.