Legal digital currency refers to the digital form of currency issued by the central bank according to law, with unlimited legal compensation, with functions of value scale, circulation means, payment means and value storage. The central bank has done a lot of work in the promotion of digital currency from the completion of the design of digital currency to the general acceptance of the public to partial replacement of cash. In this process, commercial banks will play an important role. Commercial banks have mature credit network infrastructure, payment network infrastructure, and relatively complete IT service systems. Therefore, under the binary model of central bank digital currency, the central bank plays the role of issuer, and commercial banks play the role of distributors.