A large-scale convective gale event was studied based on conventional observation data, automa-tic weather station data， 6 h GFS analysis data with 0.25°×0.25° spatial resolution, Doppler radar data, and FY-4 satellite data in East China on 12 April 2020 under the background of consistent northwesterly air flow from the lower to the middle layer behind the North China cold vortex. The results demonstrate that after the strong cold air gales moved southward on the morning of the 12 April, a convective storm was triggered near the drylines at the junction of Shandong and Jiangsu provinces in the afternoon under the favorable thermal background of cold advection at the middle level and warm advection at the lower level. The convective storm occurred in the area with a large temperature difference between 850 hPa and 500 hPa. The convective system was strengthened with favorable conditions such as better water vapor condition, stronger wind speed in the middle layer, merged gust front and the influence of the special land and sea distribution in Hangzhou Bay, which caused the large-scale convective gale weather in Jiangsu, southeastern Anhui and northern Zhejiang again, and the extreme gales at scale 13 near the Zhoushan Islands. The extreme gales occurred at gaps in the convection system and near the northeast side, caused by the rear inflow jet and the intense downdraft, smooth underlying surface, fast-moving convection system and small-scale downburst currents within the system.