This paper is mainly about the typical stable，low-motion，long-life warm southwest vortex rainstorm process on July 26-27，2023. Based on the analytical field data of the Southwest Regional Model（SWC）and the precipitation data of weather stations，the paper studies the evolution of the horizontal and vertical structure of the southwest vortex at different stages of its life cycle and its relationship，in terms of space as well as time， with heavy precipitation. The research results are the following. First of all，there are five distinct stages within the life circle of the Southwest vortex causing the rainstorm on July 26，2023：initial，development，peak，maintenance and decay. Secondly，the horizontal and vertical structures of the southwest vortex show asymmetric characteristics，and the dynamic and thermal structure of the low vortex differ in different evolution stages，thus affecting differently. In the initial phrase，the release of latent heat of condensation in the convergence uplift enhances the low vortex，and relies more on the transformation of the total potential energy to the kinetic energy， causing the low vortex to escalate. Since the strong dry cold air moving south weakens the transport of southerly warm humid wind and vapor，the atmospheric Stratified stability increases，and the low vortex attenuates accordingly. Finally，the synergistic effect of thermodynamic and dynamic forces is the main cause of the warm vortex rainstorm. The precipitation at the early stage of vortex development occurs in the warm and wet area around the vortex center，while that at the strong stage occurs on the side of the strong warm and wet airflow channel，with the intensity of precipitation corresponding well with that of vortex. Pseudoequivalent potential temperature and convergence are the key parameters indicating the precipitation area and intensity of the southwest vortex.