Abstract: A path planning method for underwater robot under condition of unknown obstacle position is proposed tomake the autonomous robot avoid obstacles and get to destination with the shortest covering distance.In re-sponse to the changing and complicate sea state,this paper implements general planning and control by intro-ducing distance error as dynamic feedback compensation.This method proposed is adaptable to path planningproblems with enviorment parameters either known or unknown.simulatibn results show it has good stabilityand adaptability.