In the context of the development of low-carbon power market. In order to improve the enthusiasm, economic benefits and transaction efficiency of each transaction subject participating in the power spot market, this paper proposes the electricity spot trading model considering carbon emission allowance based on blockchain technology. Firstly, combined with decentralized blockchain technology, this paper constructs a blockchain spot trading mechanism that takes into account electricity and carbon emission rights trading. Then, Aiming at maximizing the benefits of each power trading subject, a clearing decision model of power spot market based on double chain transaction mechanism is established. Finally, case study is performed to verify validity and superiority of the model.