In order to reduce the maintenance volume and the loss caused by the typhoon, we carried out a study on the navigable depth of the approach outer channel of Yangshan deepwater port area within the typhoon period. Based on the density, salinity and particle analysis of the bottom sediment and mud sample in the channel and shoal, and a research on the waterway sediment characteristics of settlement, rheological property and sediment incipient, we put forward the navigable density of waterway in Yangshan port area, and gain the seaworthiness bathymetry applying the SILAS measure system, which has good promotional value in the maintenance of silty port.