Abstract: In the view of actual collision between manipulators and obstacles and C-obstacle feature,the critical collision joint angle(CCJA) is defined in this paper,followed by a C-obstacle boundary modeling method based on CCJA. This algorithm has less computation and can be integrated with the robot dynamic simulation conveniently. A modified A^* algorithm is employed for path search,which has dynamic changeable steps and a goal visibility test,and has a rapid search speed,a global-path optimal algorithm is used to get optimal paths. The simulation results show that the algorithms presented here are practical and efficient for path planning of manipulators in structured and static environment.