Ant colony algorithm, as a Bionic algorithm that mimics the foraging behavior of ants, is often used as a priority for path planning. However, the general ant colony algorithm has a large amount of calculation and is prone to local optimization. In order to improve the search speed of the shortest path, a new heuristic factor based on direction angle was established, which made the ant choose the node with small angle as the next moving node. At the same time, the reciprocal of the more complex diagonal distance was used as a new heuristic factor. The distance formula was not needed to perform square root operation, the solution was simple, and the search efficiency was improved again. The experiment shows that the search efficiency of the shortest path is three times higher than that of the original ant colony algorithm, under conditions of same shortest paths. Meet the real-time path planning requirement of mobile robot in complex orchard environment.