Abstract: Sudden siltation often occurs in the port channels of muddy coasts in southern Zhejiang Province during the typhoon period, with differences in sudden siltation of different types of navigation channels. It is of great significance to study the characteristics and causes of sudden siltation for port channel construction, operation and maintenance. The siltation data of navigation channels and trial trenches in different coastal areas of southern Zhejiang Province before and after strong wind days were collected. By combing these with the data of hydrodynamic conditions, shoal distribution, sediment concentration and floating mud, the characteristics and causes of sudden siltation in different navigation channels of muddy coasts were comprehensively analyzed. The results show that the sudden siltation in the open sea area of southern Zhejiang Province during the typhoon period is about 1~2 m, while the sudden siltation in sheltered sea area is relatively small, about 0.1~1.0 m, and the sudden siltation of the navigation channel is often accompanied by a thick floating mud layer. Wave shielding conditions, sand source conditions and human activities are the main factors causing the difference in sudden siltation. The wave shielding conditions of Yueqing Bay are good, and the sudden siltation is relatively small. The sand source mainly comes from the surrounding shoal, and the sudden siltation intensity of the navigation channel has a strong positive correlation with the area of the surrounding shoal. By blocking the sand source of the surrounding shoal and enhancing the hydrodynamic strength of sediment transport, the sudden siltation of the navigation channel can be effectively reduced. The research results provide reference for the prevention and control of sudden siltation in different types of navigation channels.