A registration and authorization method, device and system is used for solving the technical problem of relatively low safety of the existing authorization technology. The method is applied to an authorization server, the authorization server is a node in a blockchain network and stores a blockchain composed of a plurality of blocks, each block is used for storing authorization information, and the method comprises: receiving a registration request message sent by a user device, wherein the registration request message includes identification information, and the identification information is used for performing identity verification on a user; assigning authorization information to the user, wherein the authorization information is used for indicating a service that the user can access; and writing the identification information and the authorization information into the blocks of the blockchain through the authorization server.