Data classification and grading have become an important component of data asset management. This article proposes a complete data classification and grading system and method to guide the classification and grading of oil and gas exploration and development data. By combining the data requirements of exploration and development business, extracting data attributes or features, and following the classification approach of closely integrating data with business, a data resource catalog was constructed. Based on this classification, a multi-dimensional classification method was used to comprehensively consider the six dimensions of data security, and the security level of the data was divided. Adopting a top-down classification approach, the exploration and development data is classified into a five layer structure and refined step by step. The security level is divided into three levels, achieving structured and organized management of data, making it easier to locate and retrieve. At the same time, it meets the requirements of data risk management, compliance, and security, achieving the effective use and protection of data, achieving differentiated management and security protection of data, and promoting secure sharing of data. The research content of this article has certain guidance and reference significance for the data classification and grading work in the oil and gas industry, and provides basic support for data security governance.