Abstract: For delivering undersea vehicle in a long range, it is extremely necessary and urgent to research the safety strategy design method of autonomous navigation. The design methods in current researches cannot meet the requirements for autonomous navigation of long-range delivering undersea vehicle with small amount of testing data because they need more sensor information and have lower universality, and higher algorithms complexity. A route re-planning method based on the drawing method, as well as a mathematical model-based depth control design method, is proposed in this paper. On the premise of ensuring safety, the shortest path and steady depth control is taken as the criterion to analyze the depth control in the conditions of flat normal water depth(including deep water), shallow water, and sudden change of depth, and control flow is given. Simulation results verify that this method is simple and universal for safety strategy design of autonomous navigation for long-range delivered undersea vehicle, and it meets the navigation safety requirements for various circumstances.