Aiming at the problems of the traditional a* algorithm in the path planning of unmanned rescue vehicle, such as too many nodes, low computational efficiency, long search time and unsmooth path, an improved a* path planning algorithm is proposed. The weighted heuristic function is optimized and the neighborhood search strategy is improved to effectively reduce the search nodes and search time while ensuring the optimal path; Bessel curve is used to smooth the path, optimize the smoothness and stability of the path, reduce the vibration of the rescue boat, and improve the efficiency and safety of the movement. Experimental results show that compared with the traditional a* algorithm, the improved a* algorithm reduces the number of search nodes by about 34.3%, 56.9% and 66.8%, and shortens the search time by 47.5%, 68.9% and 79.3%, respectively. This optimization greatly improves the efficiency and search speed of path planning, making it more suitable for the path planning task of unmanned rescue vehicles in complex environments.