To solve the path planning problem of mobile robots in complex orchard environments such as irregular and rugged terrain in hilly and mountainous areas, an improved grey wolf algorithm based 3D path planning method for mobile robots was proposed. By simulating the actual geographical environment, a three-dimensional orchard terrain and obstacle model was established, and a path planning objective function model was structed. By introducing the sparrow search algorithm (SSA) the initialization method, convergence factor, local search ability, and global search ability of the standard grey wolf optimization (GWO) were improved. The simulation experimental results show that the proposed algorithm has the advantages of fast optimization speed, optimal path planning distance, and fast convergence speed compared to other algorithms, indicating the effectiveness and superiority of the proposed method.