Abstract: Three-group stepwise discriminant analysis has been employed to diagnose and forecast the distributive patterns of summer rainfall in eastern China. The results show that the distributive patterns of summer rainfall in China could be diagnosed by using the summer rainfall for the six different stations. Based on the winter 500 hPa polar vortex area indices and teleconnection patterns intensity indices, three-group discriminant functions are established, in which only 7 predictors are included. The fitting frequency is 38/39 for the 39 years data. The test forecast result of 1991 is correct. It can serve as a valuable objective forecast model to the patterns of summer rainfall in eastern China.