Abstract: A robot intelligent path planning system(RIPPS), which can be used as a robot off-line programming tool was introduced in this paper. C-space modeling and path search are key parts of the system. A fast C-space modeling is presented based on critical collision joint angle(CCJA), C-obstacle boundary can be computed by the feature points of obstacles. A modified A^* algorithm is used for path search, although the path is slightly sub-optimal, a tremendous speed increase is achieved. RIPPS runs on a Silicon Graphic 4D/70 workstation, simulation results show that the system is efficient and practical for robot collision-free autonomous path planning in a structured and known environment.