Abstract: In 2022,the rainfall in the Yangtze River Basin and the water discharge from the main tributaries were severely low, and the water level of rivers and lakes continued to decline, the worst basin-wide meteorological and hydrological drought occurred since complete records began in 1961.Affected by this, the Yangtze River estuary had encountered saltwater intrusion in late August 2022,which was the earliest event monitored.The saltwater intrusion was then intensified and continued to affect the Yangtze River estuary.This study analyzed the dynamic process of saltwater intrusion in the flood season by using the data of the Yangtze River estuary observation system including shore stations and buoys.FVCOM numerical model was used to quantify the effects of runoff, tides and typhoon events on saltwater intrusion.The summer runoff in 2022 was the lowest in history, resulting in the earliest saltwater intrusion, with the frequency as well as the intrusion distance both increased.The salinity on the north side of the river was significantly higher than that on the south side.The saltwater intrusion under low runoff conditions showed a significant variation with tide from flood-ebb to spring-neap cycles.During late neap tide, there was rapid increasing in salinity.It then turned to slow decrease of salinity during spring and transient tide.In addition, the persistent northerly winds also enhanced the magnitude of saltwater intrusion resulting from increased onshore water transport and raised water levels.In September 2022,under the influence of Hinnamnor and Nanmadol typhoons, the saltwater intrusion reached up to about 10 km north of the Dongfengxisha Reservoir during the flood tide period.The saltwater intrusion reached its greatest extent on September 21.