Abstract: The conventional energy saving control method of building electrical lighting system mainly uses DIALux software to build a Room Element building energy saving model, which is easily affected by the light density of lighting calculation, resulting in poor energy saving control index. Therefore, an energy saving control method of building electrical lighting system based on particle swarm optimization algorithm was proposed. That is,the energy-saving control model of the lighting system is constructed by particle swarm optimization algorithm, the energy-saving fuzzy controller of the building electrical lighting system is designed, and the energy-saving clock chip control process of the building electrical lighting system is generated, so as to realize the energy-saving control of the building electrical lighting system. The experimental results show that in different energy-saving control periods, the energy-saving control method designed in this paper has good control indicators, has reliability and application value, and has made contributions to meet the requirements of energy use and promote the green and sustainable development of buildings.