In order to solve the problems of high cost, slow speed and lack of privacy protection of continuous double auction block chain, a privacy protection scheme for microgrid direct transaction based on alliance block chain and continuous double auction is proposed. After the consumer and the producer are matched through a continuous double-auction mechanism, the consumer confirms the authenticity of the account and the electricity charge sent by the producer and creates a transaction record; Electricity producers send electricity bills and transaction records to local aggregators, encrypt them, and package them into blocks to broadcast verification to each aggregator node. The experimental results show that the proposed scheme has lower computational overhead and energy consumption, and provides a reference for the intelligent and secure application of electricity trading.