Abstract: Based on conventional meteorological observation data and encrypted ground automatic station data, the mesoscale convective conditions and causes of local heavy rain in Guang 'an City on 17 June 2020 were analyzed. The results show that the rainstorm occurred in the southwest airflow in the northwest side of the subtropical high and in the front of the trough. The main reasons for the development and maintenance of convective precipitation are abundant water vapor, the superposition of warm advection and middle-high level southward cold air, and high unstable energy. The obvious warming and humidifying process makes the convective conditions in the central and eastern part of Guang ’ an better than those in the surrounding areas. In addition, the combined influence of topography and surface wind field strengthens the triggering uplift conditions, resulting in the occurrence of local heavy rain weather process.