In order to improve the rationality and economy of distribution network maintenance plan, an optimization method of distribution network maintenance plan based on improved particle swarm optimization is proposed. Firstly, with the goal of minimizing maintenance cost, power supply loss, and failure loss, and the constraints of maintenance resource limitations, maintenance sequence, and safe and stable operation in the actual maintenance process, a maintenance plan optimization model that conforms to the actual distribution network maintenance process is established. Secondly, corresponding preprocessing methods are proposed for different types of constraintsto reduce the complexity of solving the problem. Finally, by incorporating the idea of natural selection into the iterative updating of population particles, the overall quality of population particles is improved to overcome the problems of premature convergence and easy to fall into local optimal solution of standard particle swarm optimization algorithm. The improved particle swarm optimization (PSO) algorithm is applied to solve a specific example. Results show that the proposed model and algorithm have good feasibility and rationality.