Abstract: In order to explore the complex multi-scale process of supercell hailstorm and the interaction mechanism of terrain environment in mountainous area of Guizhou, a multi-scale comprehensive analysis of a supercell hailstorm process in Guiyang area on April 4, 2012 was conducted by using Doppler radar observation data, ERA-5 reanalysis data and WRF mesoscale model. The results show that: (1) The southbound 500hPa upper-level trough, 700hPa low-level shear line and 850hPa low-pressure cyclone, together with the unstable stratification of "cold above and warm below", the ground convergence line and the uplift of mountainous terrain, jointly triggered and maintained the supercell hail storm process. (2) The hailstorm process of the three supercells lasted for about 3 hours, and the combined reflectivity was greater than 65dBZ, the echo top height was more than 11km, and the bow echo and three-body scattering phenomenon appeared. The vertical wind shear of 24m/s is the main reason for the formation of mesocyones. The center of hailstorms is from -10℃ to 0℃, which is conducive to the formation of hailstorms. Strong mesocyones at low and middle levels promote air convergence and rise, and the velocity "0 line" channel helps water vapor and energy transport. (3) The vertical velocity of 900hPa-200hPa elevation layer increases, the strong updraft provides power for the development of hail storms, the high relative humidity in the middle and low levels provides water vapor, and the water vapor condensation releases latent heat to promote the development of convective movement. The potential vorticity is positive on the upper side and negative on the lower side, which shows that the structure of atmospheric thermal vortex is conducive to the development of convection. In the early stage of development, the vertical physical quantity exchange is less, the convection is weak, and the potential vorticity and thermal helicity are obvious indicators. In the mature stage, the instability is aggravated by the strong updraft in the vertical wind field, and the indications of potential vorticity, water vapor helicity and thermal helicity are obvious. In the dissipation stage of hail, the vertical velocity decreases, the relative humidity and water vapor flux change, the potential vorticity magnitude decreases, and the water vapor helicity and thermal helicity indicate the system tends to stabilize, hail and collapse. (4) The cloud water content of 500hPa-900hPa fluctuated successively, the rain water of 700hPa-900hPa appeared from 9 to 10 and continued to increase, the snow water content of 300hPa-600hPa changed steadily, and the ice water content increased in some areas. The simulation shows that a large number of cloud droplets are formed from 0℃ to -20℃ in the hail cloud, raindrops are formed under the layer of 0℃ and ice crystal particles are formed at -40℃, and graupel and snow particles are formed at -10℃ to -40℃ through the Begeron process, and graupel particles are formed when they dry and freeze into hail particles. In the mature stage, cloud droplets are transformed into raindrops or ice crystals, and hail particles are formed through a series of freezing and adhesion processes. In the hail fall stage, graupel particles generate hail in the large value area of supercooled water, and the hail rises and falls repeatedly in the front end of the hail cloud in the "acupoint" - "zero domain", and becomes a massive hail in this area, and then the hail finally falls in the back end of the hail cloud.