The invention belongs to the technical field of intelligent power grid information security, and discloses a power system security and stability control terminal identity authentication method based on a block chain, and the method comprises the steps: voting new equipment A applying for network access by a node on the chain of an authentication block chain based on user identity information; enabling the new equipment A to send a communication authentication request to equipment B according to the identity of the equipment B, and send the last item of the own authentication key sequence to the equipment B at the same time; and after the authentication is passed, enabling the equipment B to send an authentication passing confirmation message to the new equipment A to allow continuous communication. Identity authentication between the safety and stability control terminals in the power system is achieved, the inherent distributed characteristics of the safety and stability control system are met, and the problem that an authentication center is fragile due to centralized management is avoided; time consumption and computing power requirements are reduced, and the operation characteristics of the safe and stable control terminal are better met. According to the invention, man-in-the-middle attacks can be defended, and the safe and stable control terminal is prevented from being illegally accessed.