The invention discloses a decentralized access control method for safe sharing of data in a smart power grid. The method comprises the following main implementation steps: 1, constructing an access control system; 2, initializing an access control system, and generating a global public parameter GP of the system; 3, initializing an authorization mechanism; 4, generating a user key; 5, generating acloud server private key, a signature public key and a signature private key; 6, generating a final ciphertext; 7, verifying the identity of the user and decrypting the message; and 8, deleting the user to be revoked from the private key list of the cloud server. According to the method, multiple mechanisms are adopted to jointly undertake tasks of the system, the efficiency of the system is improved, a large amount of encryption and decryption calculation is carried out by the cloud server, the calculation overhead of a data user is saved, and zero knowledge is added to prove that the identity information of the user is protected in the interaction process of the user and multiple authorization mechanisms.