Abstract: The data security law proposes that "the state establishes a data classification and grading protection system", which determines that classification and grading is an important system for national governance of data security. The existing data classification and grading method has a single perspective and is mainly based on the sensitivity of data, which is not applicable to the scenario of complex types and diverse attributes of power data. This paper proposes a multi-dimensional classification method, which comprehensively considers the influence object, influence scope, influence degree, data sensitivity, relevance to production business and business system of data security. The security level of power data is divided into 1-4 levels from six dimensions, and an operation example is given. The data classification and grading method proposed in this paper solves the problem of consistent commercial confidentiality protection guidelines, Ministry of Industry and Information Technology data classification and grading guidelines, and national level protection compliance, and provides basic support for realizing power data security governance.