Power big data covers all links such as power generation, transmission, transformation, distribution and consumption, featured with the characteristics of wide data sources, complex data structure, high real-time requirements and containing a large amount of sensitive information. During the sharing process, once the data is leaked, it will not only infringe upon the privacy of users, but also threaten the safe and stable operation of the power system. It has significantly increased the difficulty of sharing power big data. Traditional methods usually complete encryption directly before data sharing, but they cannot ensure the security of the encryption environment for power big data, resulting in the problem of theft still occurring during the sharing process. Therefore, a secure sharing technology for power big data based on consortium chain and attribute encryption is proposed. A power big data sharing platform is established based on alliance chain, on the consortium chain, attribute encryption methods are used to set encryption access strategies for power big data. The consortium chain can provide a trusted environment where all parties can record the sharing process and usage of data through blockchain, ensuring that only users who meet specific attribute conditions can access the corresponding power data; based on Lagrange interpolation and Shamir secret sharing scheme, power data is segmented and distributed to ensure the security and privacy of power data during the sharing process, while improving the efficiency and flexibility of power data access. The experimental results indicate that the proposed data security sharing method is more suitable for practical applications and has higher security.