In order to improve the illumination uniformity of the light emitting diode (LED) light source array, an improved particle swarm algorithm and a new arithmetic LED array arrangement method were proposed. According to the illumination distribution model, the illumination uniformity evaluation function of the illuminated surface was established, and the improved particle swarm algorithm was used to optimize the new arithmetic, rectangular and circular LED arrays. The data of the optimized LED array was imported into the optical software TracePro for simulation and verification, and the illumination uniformity of the optimized arithmetic, rectangular and circular LED arrays was 82.89%, 73.31% and 78.56%, respectively, which was 15.84%, 10.65%, and 15.57% higher than the illumination uniformity of the LED array before optimization. The research results show that the improved particle swarm algorithm has faster convergence speed and higher convergence accuracy, and the proposed new arithmetic LED array has better illumination uniformity.