The invention discloses a cloud computing based power data security storage method. The method comprises the following steps: (1) a user applies for a cloud storage space through a service interface, accesses a cloud computing framework to visit data, and selects whether the data need to be encrypted or not; (2) the cloud storage space is distributed to the user, if the data need to be encrypted, a key is distributed according to an algorithm, and a mapping relationship between the storage space and the key is stored; (3) after the cloud storage space is distributed, the user is notified to enable cloud storage resources; (4) the user accesses cloud storage according to an applied business mode, and when the user writes the data, encrypted ciphertext data fall in a storage system; and (5) when a legal user allowed by business reads cloud storage space data, an encrypted data block is decrypted and recovered into a plaintext, and the plaintext is returned to a user interface.