Abstract: In order to understand the effect of MCC on the rainstorm process in Guizhou mountain area, the rainstorm case on May 27,2008 is analysized with the observation data and reanalysis data. The Results show that the overlaying of warm moist air flow in the lower troposphere and dry cold air in the middle level strengthens the convective instability. The low-level warm shear makes the convective cloud cluster develop into a MCC, and the cold shear makes the MCC weaken and disappear. During the formation and development stage, the rain cluster presents NW-SE and less moves. The axis of the MCC is east-west along with the warm shear at 850 hPa, and the MCC spreads at the same time in both sides of the warm shear. When the MCC begins to weaken, the rain cluster moves southward, and spreads in the cold high pressure belt and then weakens. The heavy rain usually occurs near the axis of the MCC where the TBB is less than -92℃ but the TBB gradient area. Wangmo and Zhenfeng are located in the east and west sides of a valley in the southwestern of Guizhou Province. When the easterly wind is up to 6m/s, the obvious orographic ascending motion occurs, which has the significant topographic effect on the rainfall in Wangmo and Zhenfeng located on the both sides of the bell terrain.