Load balancing is crucial for distribution network operation. This paper introduces an optimization method of complex distribution network operation with trigger rules to improve load balancing. The state evaluation system of distribution network is established from the perspectives of security, economy and reliability. Based on the objective weight method of CRITIC, a comprehensive evaluation model is established to complete the objective weighting of each index. The comprehensive threshold is set according to fuzzy set. The linear optimization model of complex distribution network is established to realize load balance among multiple zones. Finally, an example is given to analyze the data of a distribution network in a Chinese city, and the effectiveness of the proposed method is proved.