Aiming at the problems of slow convergence speed, low search efficiency and poor solution quality of traditional ant colony algorithm in three-dimensional path planning of autonomous underwater vehicle, a three-dimensional path planning method based on improved Empire competition algorithm is proposed. This method takes the traditional imperial competition algorithm as the framework. Firstly, the ant colony idea is introduced into the national initialization part to search the initial path and improve the quality of feasible solutions; Secondly, in order to ensure that the algorithm will not lose excellent individuals while improving population diversity, the idea of differential evolution is added to the part of colonial revolution; Finally, the simulation comparison is carried out on three maps of different scales. The simulation results show that the improved imperial competition algorithm makes full use of the characteristics of fast convergence speed, high convergence accuracy and strong global search ability of the traditional imperial competition algorithm, improves the accuracy of the optimization process, strengthens the global optimization, effectively solves the problem that the traditional imperial competition algorithm is easy to fall into the local optimal solution, and the length of the optimal path is shortened by 11%.