Abstract: By using NECP 10×10 re-analysis data numerical to analyze a continual rainstorm process in Bazhong city from July 16 to 18, 2010, the results show that the subtropical high and the kangsen play the choking action to the low value system, the mutagenesis of rainstorm are the jet flow and the southwest vortex.The moisture flux divergence, relative humidity thickness, vertical velocity, underlying bed vorticity, preudo-equivalent potential temperature and so on physical factors display in this rainstorm process are very obvious, they are the very good method for forecasting the long-enduring rainstorm.