Nowadays, the nested grid model is widely used to increase the resolution of numerical model.An attempt to investigate the influence of the newly developed nesting technique of WRF model on the mesoscale numerical simulation of severe storm is described in this article.The results of sensitivity tests infer that the WRF model give more accurate and vivid prediction of severe storm with nesting scheme.As is shown in the tests, simulating value of the precipitation centers using nesting scheme are larger than those without using nesting scheme, which indicates that the simulating precipitation of nested storm is closer to the real rainfall.And there is obvious improvement of distribution of rain area and position of precipitation centers.According to the high resolution output data of the WRF model, deep and detailed analysis of characters of the mesoscale system that triggers the rainstorm is reported in this article, and the thermal and dynamical characters of this Meiyu front severe storm are also discussed.