Zhoushan Putuo District Xiaogan bridge links the Zhoushan island with the Little Gan island, and spans the Shenjiamen west harbor area.Shenjiamen fishing port is famous in our country.It is a comprehensive port for fishing boats’ sheltering, re-supply, aquatic products distribution, and passenger transportation.Shenjiamen west harbor channel is surrounded by Xiaogan island, Mashi island and Zhoushan island.There are many terminals on both coasts, and the ships’composition is more complicated.Based on the analysis of the hydrographic conditions, the navigation condition and port situation of Shenjiamen west harbor area in Xiaogan bridge area, we analyze the site location of Zhoushan Xiaogan bridge to be constructed, and calculate the navigation span from the view of navigation. We also demonstrate on the navigable clearance based on the channel condition in the bridge area.