Abstract: In August 2020, under the combined effects of the westward movement of the subtropical high pressure, the movement of the cold high pressure center to the edge of the Sichuan Basin and the southwest mountainous region, and southwest vortex, extreme heavy rainfall occurred in Jialing River basin and Minjiang River basin. Serious floods encountered in the main streams and tributaries of the Yangtze River, and the biggest inflow flood also occurred in the Three Gorges Reservoir since its establishment. Based on the operation data of the controlled hydrological stations and hydropower projects in the main streams and tributaries of the Yangtze River, the representative hydrological natural inflow process was restored. The regulation and storage function of the upstream controlled reservoirs, the flood encounter characteristics of the main and tributaries, the flood peak discharge and the flood volume in different periods of the representative hydrological stations in 2020 were analyzed, and the flood return periods were also determined by combining historical flood data, so as to better serve for the flood control and the reservoir operation on the main streams and tributaries of the Yangtze River.