In the application of path planning for mobile robots, jump point search (JPS) is widely used because of its simple, rapid-and easy-to-implement characteristics. However, the standard JPS algorithm with a low efficiency of heuristic function is prone to hold redundant nodes in the planned path. Besides, the JPS often neglects the path security. To address these issues, this paper proposes an improved JPS algorithm. The proposed algorithm designs a novel heuristic function combining diagonal distance and direction information to improve the path-finding efficiency, and further smooths the planned path for guaranteeing safety and reliability. The path-planning experiment for mobile robot in the obstacle environments demonstrates that our algorithm obtains higher path-search efficiency with reducing the planning time and improving the safety effectively, compared with other advanced path planning algorithms.