Abstract: Based on conventional meteorological observations,hourly observation data from meteorological stations in the ground region,FY-2G cloud top brightness temperature,CR/CC radar products in Kashgar and NCEP reanalysis data, The circulation background,and mesoscale characteristics of two extreme rainstorm processes from April 17 to 24,2020 and June 15 to 17,2021（Process 1 and Process 2,respectively）in western Southern Xinjiang were compared and analyzed.The results show that both processes took place under the favorable circulation background of “east-west attack”at 500 hPa,and the 100 hPa SAH was east type and double type,respectively.Low-level jet,shear line,and surface mesoscale convergence line were the critical triggering systems of the two heavy rainstorms.The two heavy rainfall events occurred when the convective cloud cluster was the most powerful and its range was the largest or the TBB gradient was the largest.However,the radar echo characteristics are obviously different.The influence system of“Process 1”is a linear multi-cell strong storm with a maximum reflectivity factor of 65 d BZ,which has the characteristics of convergence and rotation at small and medium scales.During the heavy rainfall,VIL maintains over 40 kg/m2and has a jump phenomenon,which is more conducive to the generation of severe convection.The system affected by “Process 2”was a dispersed typical mono storm,with no apparent divergence in the upper level of radial velocity.The Value of VIL was significantly smaller than that of“Process 1”.