The paper proposes a high-dimensional multi-objective reactive power optimization model of power system. Compared with the traditional power system reactive power optimization model, the proposed model can balance the active loss, voltage level, static voltage stability and power supply capacity in reactive optimization. Owing to the limitations of the existing algorithm for solving the multi-objective reactive power optimization model, a new high-dimensional multi-objective particle swarm optimization algorithm based on Pareto entropy is introduced and improved further in this paper to effectively solve the high-dimensional multi-objective optimization problem. Finally, the correctness and validity of the proposed model and the algorithm are verified by IEEE-39 node system. In addition, the simulation results show that the introduction of power supply capacity into traditional multi-objective reactive power optimization model can improve system’s power supply capacity with no deterioration in optimization of other objective functions. This work is supported by National Natural Science Foundation of China (No. 51677069).