Concerning the low accuracy, poor stability and security of the path planning algorithm of tractor-trailer mobile robots system, a path planning algorithm based on path-following method was proposed. On the basis of Rapid-exploring Random Tree (RRT) method and the equations of path-following, the path accuracy was improved by automatically fitting spline curve and tracking and generating the path between nodes; an angle constraint condition between systems and node hitting mechanism were added to the algorithm to improve the stability of algorithm and the security of results. In addition, an optimization algorithm based on greedy strategy was added to optimize results. The simulations results indicate that compared with the basic RRT algorithm, the path calculated by the improved algorithm is more close to the actual trajectory, and the success rate and security are better than the original algorithm, which can meet the requirement of quick design and real-time systems.