Abstract: Numerical simulations are made with the newgeneration numerical model WRF(Weather Research and Forecast)and MM5 on three typical heavy rainfall processes happened in 1998.The three heavy rainf all processes happened respectively over South China in May,over Huaihe reach at the beginning of July and over Yangtze river reach at the end of July.It is clear that the different results of the newmeso scale model WR Fcan successfully simulate the rainfal processes which have different characteristic.And to all these three processes,WRF makes much better simulations than MM5,not only about the distribution of the precipitation,but also about the major weather systems.In all these processes,the movement of the major weather systems is simulated by WRF successfuly,such as in the first process happened over South China,the cold air stream came from the North China and a vortex over the South China are both reproduced correctly by the model,and this good reproduction of the weather pat terns could also be seen in the two other heavy rainf all process.It is clear that this is the main reason that WRF makes the bet ter simulation of the distribution of the precipit ation.But unfortunately,the maximum values of the precipitation center are much less than the results of MM5,and also less than the observations.From the numerical results,wefound that the respectively smal vertical velocity simulated by WRF can be considered as the major fact or for the small precipitation.