The formation and evolution of the supercell that happened in Chengdu on 7 August 2016 were discussed. Based on Chengdu Doppler Weather Radar， windprofiling radar， and densely laidout automatic station observation， the contributing factors of the mesoanticyclone were studied in this paper. The results are as follows. The mesoanticyclonic supercell was formed under the northerly airflow in the west of the upper cold vortex, with strong cold advection in middle and upper levels. The convective instability energy (CAPE) reached 5 〖KG-*5〗029.7 J·kg-1, the temperature difference between 500 hPa and 850 hPa was 29℃, and the wind shear vector difference between 500 hPa and 925 hPa was about 16 m·s-1. The sounding as a whole took on the shape of a bell mouth, in which the upper level was dry and cold while the lower level was warm and wet. The existence of lowerlevel inversion was conducive to energy accumulation. Thunderstorms were triggered by westward winds under the forced uplift of Longquan Mountains, while downward flow produced cold outflow and triggered new cells continuously on the north side.Thunderstorms and new cells merged into supercell. The mesoanticyclonic supercell storm was accompanied by the echo characteristics such as lowlevel strong convergence, mesoanticyclone, rear inflow, rear inflow gap, vortex couple, etc. The formation of mesoanticyclone in S1 supercell storm was formed via merging the lower and middle levels. For lowlevel mesoanticyclones, small eddies were generated when thunderstorm and cells merged. The baroclinic vorticity was caused by the intrusion of dry cold air and warm wet updraft, which caused convergence to rotate. Thunderstorm developed strongly under strong convergence, and strong upward motion caused vertical vorticity to stretch, increasing rotation. For midlevel mesoanticyclones, the horizontal vorticity in the height range of 3-4 km was about 1.2×10-2 s-1, which was beneficial to the formation of horizontal vortex tubes. Vortex couples were generated under the strong updraft and downward airflow. The anticyclones were developed by counterclockwise rotation of midlevel and highlevel winds.