Abstract: By Using FY4 satellite, weather radar and encrypted automatic station data, the mesoscale characteristics of the rainstorm in Mianning on June 26 were analyzed. The results show that: Shear line at 700hPa, cold advection, strong unstable energy, unstable stratification were very conducive to the development of strong convection. The key system of trigger convection in early stage was the shear cloud in Jiulong, which triggered convective cloud clusters as it descended the mountain. The strong precipitation area was located in the southern of the strong brightness temperature area, and the initial time of heavy rainfall lags behind the development time of MCS. Downdraft was generated in the thunderstorm, which led to the continuous increase and maintenance of the northerly gust on the ground, then new thunderstorms were triggered at the convergent point of the bell mouth topography and the southern convergence. Under the action of low-level southerly winds, the new thunderstorms continuously merged with the mother thunderstorms on the north side, forming obvious backward propagation characteristics. At the same time, under the blocking action of mountains, the thunderstorms maintained for a long time and moved slowly, which eventually led to the persistent heavy precipitation in Mianning .