Abstract: This paper presents the design and implementation of a map based path planning and navigation system(MBPPN)for an outdoor mobile robot. A simple object-based spatial representation,based on the thematic component layering as well as topologic features of spatial relationships,is proposed. Global path planning allows finding optimal paths under multi-constraints.The cost function of a heuristic search algo-rithm takes into account both the length of the path and the number of turns.A navigation system model by using a finite state machine is described.Several experimental results which are implemented in a SUN 3/260 Workstation In accordance with Our campus environment are also given in this paper.