Abstract: The sudden loss of control during navigation of a seagoing vessel will bring great risks while in waters with high traffic density. Emergency anchoring is the last available measures to the vessel herself. The appropriate length of the chain is related to the effectiveness of emergency anchoring and will have a direct impact on the consequences of losing control because the chain is too short to achieve the desired effect while the chain is too long can easily break or even losing the anchor. Based on the analysis of the chain tension during emergency anchoring,this paper calculates the force on the chain at different ship’s speeds corresponding to different length of the chain,compares the chain safe load,and puts forward appropriate length and safety operation during emergency anchoring,It has been verified in practice and is expect to provide a certain reference for emergency anchoring.