The Yongzhou Railway from Ningbo to Zhoushan is an important link for Zhoushan to integrate into the national high-speed railway networks. The tunnel line through the Jintang waterway faces the buried environmental risks caused by the excessive natural water depth，local limit scour，anchor dropping，or dragging of large ships during navigation and mooring. The paper has comprehensively combed the current navigation conditions and anchorage conditions of the Jintang waterway，and carried out special studies on historical coast evolution，limit erosion and deposition analysis，anchor drop and towed anchor strike depth，etc.The study has proposed the local minimum buried depth and the along with requirement the buried dimension of the Yongzhou Railway tunnel passing through the Jintang waterway，which has provided important technical support for the longest undersea rail tunnel construction in our country.