Abstract: Using ERA5 reanalysis data and GPM satellite precipitation products, the correlation between gravity waves and the southwest vortex at different stages of a heavy rain process in Sichuan Basin from August 25 to 26, 2023 was analyzed, in order to deepen the understanding of the interaction mechanism between gravity waves and southwest vortex. The results show that: Mesoscale gravity waves are stimulated by shear instability and ageostrophic convergence and divergence mechanism near 300 hPa. The divergence region associated with gravity waves extends eastward to the Sichuan Basin and triggers the release of unstable energy. Combined with the weak trough at 500 hPa and the favorable thermal and dynamic conditions of the basin, the vertical motion of gravity waves in the east side of the cloud belt develops rapidly and strongly. After the rain belt from the north of the gravity wave moves eastward into the Sichuan Basin, the north wind strengthens and the cyclonic wind shear originally generated by the south wind develops, and the circulation tends to close, resulting in the southwest vortex. When the rising branch of gravity wave is located between the two rising motion centers in the southwest vortex circulation at 700 hPa, the updraft extends above 400 hPa and forms a secondary circulation circle, resulting in cumulonimbus clouds throughout the troposphere. When the rising branch of gravity wave occurs high-level in the downstream of the updraft of the southwest vortex, the gravity wave cloud system can develop downstream, and there is a weak rainfall area generated by the upper cloud system and extending downstream. Whether the updraft in the southwest vortex is coupled with the updraft branch of gravity wave is the key to the further development of gravity wave cloud system and the expansion of precipitation range.