The electricity is essentially a function of electricity customers and their electricity consumption. The electricity contract generally stipulates the calculation method of electricity price rather than one or a set of clear and fixed prices. The electricity price is subject to provincial policies, user classification, electricity price type, The impact of new energy, etc., will generate electricity charges, refunds and other services. In addition, in the absence of unified national supervision, it is difficult to update the electricity billing system in each province, and at the same time, the calculation of electricity bills is extremely complicated. This paper proposes a general billing algorithm based on ordered tree, which can construct a variety of complex rules through flexible assembly of basic rules, which can meet the billing needs of utility companies. The power charge engine implemented based on this algorithm can adapt to the different electricity bill calculation rules in different provinces, changing the unfavorable situation that the original marketing system lacks a unified billing module, and it is difficult to quickly respond to government and market requirements, as well as the headquarters’ management and supervision requirements for provincial and municipal companies, and the operating efficiency is higher than the original hard-coded billing module. Finally, the power charge engine also effectively improves the versatility, reliability and operational efficiency of the existing State Grid marketing system.