Based on multi-source observation data, FY4 satellite data and ERA5 reanalysis data, the evolution of circulation situation, the occurrence and development of mesoscale convective system and satellite cloud images of a Southwest China vortex rainstorm weather process in the east of Sichuan-Chongqing Basin from June 26 to 27, 2022 were diagnosed and analyzed, and the development and maintenance mechanism of the Southwest China vortex that caused the rainstorm process were studied by using vorticity equation. The results show that: (1) This process was a Southwest China vortex rainstorm weather process formed by the cold front carrying cold air near the ground and the low-level southerly warm and humid air under the favorable cooperation of the multi-scale weather system. (2) The large-scale circulation system provided dynamic uplift conditions for the development and deepening of the Southwest China vortex, and convective cloud clusters and strong precipitation areas were mainly distributed on the east side of the low vortex and near the low-level shear line in the strong dynamic uplift area. The warm and wet transport of the southwest airflow at night promoted the gradual expansion and continuation of precipitation range. (3) The development and maintenance of vortex were mainly affected by the advection term and horizontal divergence term of vorticity, in which the geostrophic component made the local vorticity continuously decrease, while the non-geostrophic wind component made the local vorticity continuously increase.