Abstract: Under extreme typhoon weather, typhoon waves may cause large suspended sediment in the bay, resulting in sudden siltation of the deep trough in the bay. Taking the central parts of Zhejiang province as the research object, this paper predicts the amount of the sediment deposition in Maotou deep pool with the influence of Typhoon In-Fa. To answer this question, a mathematical model of sediment erosion and deposition under the combined action of waves and currents is established. The mathematical model reproduces the storm surge and typhoon wave process. The results show that under the action of typhoon waves, the sediment concentration in the south shoal of Xiayangtu and the north and south shoals of Maotou deep pool increases significantly, which can be increased by more than three times in some part, the maximum siltation of Maotou deep pool is 0.15 m. The increase of sediment concentration caused by typhoon wave is the main reason for the sudden siltation of Sanmen Bay deep pool.