Computation time and voyage were optimized as objectives whereas maneuverability of the anti-ship missile, maximal flight, all kinds of obstacles were considered to be constraints, and path planning methods were presented for pre launch route optimization of an anti-ship missile based on adaptive A* algorithm and improved generic algorithm. In improved A* algorithm, sub-optimal path was obtained by constructing a network in which node distance and node intensity could be changed adaptively with respect to operation environment in the search time. With this method, closer optimal path was found out in less computation load, furthermore, it could solve the problem of path planning in particularly complex environment. In improved generic algorithm, through using real-valued encoding technique and intelligent creation method for initial population, feasible individuals only were created which had variable-length chromosome and real-valued encoding. The problem was solved for low search efficiency due to a great deal of infeasible solution in initial population. Finally, simulating experiments were done to use two proposed improved method in different operation scenario. The results show that the first method is suitable for real-time path planning in complex operation zone, whereas the second method is suitable for high-precision path planning problems in pre-launch phase.