Most parking guidance system is not perfect, in an unknown and complex parking lot, the most urgent problem to the driver is how to find a parking space and find his car from the parking space quickly. In order to solve this problem, in virtue of the improved layered A* algorithm, system fast calculates the optimal path information which is from the entrance to each parking space and from each parking space to the export. Compared with using A* algorithm directly, the calculation time is shorten, the number of traversal nodes is reduced. At the same time, it adopts the integration design idea in the design of hardware and software, and uses international popular CAN to complete the design of network nodes in the parking guidance system, in which the monitoring interface is designed, the parking space information and gateway vehicle information are collected, the optimal path information are displayed. As integration design method was adopted, the design contents are simplified, the development hours are shortened, and the CAN intelligent nodes have a good extendibility and portability. This is the foundation for the expansion of parking lot In the future.