Abstract: In the context of increasingly accurate investment in power grid projects, based on combing the current power grid project cost management process, this paper makes a comparative analysis of the completed power grid project investment plan and budget deviation rate and balance rate, and analyzes the main influencing factors of cost deviation from the perspective of itemized cost. According to the main problems of each responsible subject in the process of project construction, the evaluation model of cost management effectiveness is established from three kinds of responsible subjects, namely, the project developer, the construction contractor and the design unit, and the multi-level fuzzy comprehensive evaluation method is used for case application and analysis. Finally, according to the analysis, the optimization strategy of cost management is put forward, which provides a reference for improving the efficiency of power grid investment and improving the level of detailed management.