The invention discloses an authorization method, apparatus and system based on an oAuth protocol, and belongs to the technical field of a computer. The method comprises the following steps: receiving a third-party authorization request sent by a third-party application client; sending a system access token to an authorization server corresponding to a service provider, wherein the system access token is a token applied for by a terminal in advance from the authorization server; receiving a third-party access token sent by the authorization server, wherein the third-party access token is generated after the authorization server verifies that the system access token is valid; and sending the third-party access token to the third-party application client. According to the invention, the problem of severely affected smoothness and convenience of an authorization process, caused by enormous repeated operation during realization of authorization of multiple third-party applications by use of a conventional authorization method related to in the prior art is solved; and the enormous repeated operation is avoided, the smoothness and convenience of the authorization process are improved, and the security of a whole authorization process is improved.