Currently, the real-time pricing mechanism of smart grid does not consider the impact of privacy information disclosure on power consumption and electricity price, and ignores the balance of interests between power suppliers and users. In order to take into account privacy protection and the balance of interests between supply and demand sides, the blockchain privacy information protection mechanism was integrated into the real-time electricity price strategy of smart grid. By classifying users and quantifying the application degree of blockchain, a social welfare maximization model was established on the basis of the application degree of blockchain. The optimal electricity consumption, supply and price were obtained by using the Lagrangian dual theory and the projected gradient method. Numerical simulations showed that the decentralized nature, currency mixing mechanism and off-chain encryption technology of the blockchain can effectively protect the privacy information of both supply and demand, reduce the cost of power supply and electricity consumption, and improve the profit and welfare of the power supplier.