The performance of RegCM3 in simulating the rainfall and associated circulation in Meiyu Period of the Yangtze-Huaihe river valleys is examined in comparison with the reanalysis data and observation. The results show that the RegCM3 can simulate the basic configuration of atmospheric circulation at high and low levels and successfully reproduce the main characteristics in the strong humidity and weak temperature gradient in the Meiyu period in the Yangtze-Huaihe river valleys. The humidity tongue of pseudo-equivalent potential temperature over the valleys and the strong gradient zone to the north are also well simulated. As a result, the Meiyu rain belt is basically simulated. Nevertheless, the simulated Meiyu front is relatively weak and the location of convective instability energy release is far south in comparison with that in the reanalysis data, resulting in the less simulated rainfall in the Yangtze and Huaihe river valleys and abundant rainfall in South China region. What is responsible for the bias and how to improve the performance of RegCM3 need to be further studied.