The invention provides a distribution network loop closing power switching power flow calculation optimization method. Through counting parameters of network elements of the distribution network, a power flow calculation model is built, and the corresponding relationship between all network nodes and a particle swarm is built; according to a preset algorithm, particles with the individual optimalvalue and the global optimal value are obtained; and finally, the active power adjustment amount of a generator of the network node corresponding to the particle with the global optimal value is outputted, and the active power adjustment amount of a load, the adjustment amount of a reactive power compensator and the gear adjustment amount of a transformer are outputted. The particle swarm algorithm has no crossover and mutation operations, searching is completed by depending on the speed and the position of the particle, only the particle with the individual optimal value transmits the information to other particles during an iteration process, and the searching speed is quick. Compared with the prior art, the optimization method provided in the invention needs to adjust few parameters, the structure is simple, and the engineering realization is facilitated. The optimization method provided in the invention is high in precision, accurate in result, short in calculation time and good inconvergence.