This paper investigates the interannual variation features of April to June precipitationand main difference in 500hPa height anomaly between drought and flood years in South China。Results show that the rainfall has a quasi periodic (2.5 to 3 year) oscillation and a 10 year or sopersistent variation as an interval feature;in the dry and wet years,the January to March 500 hPaanomaly patterns are basically in anti-phase and the April to June patterns differ widely.Comprehensive analysis indicates that the evolution of 500 hPa height anomaly from winter to the following June follows a roughly opposite direction along the 50°N parallel in the two types of years。