The invention belongs to the technical field of cloud data security with a protocol as a feature, and discloses a cloud data multi-copy integrity verification and correlation deletion method and a cloud storage system. The method comprises the following steps that a user randomly generates a data key to encrypt a file copy, and meanwhile, the user encrypts a data key by using a control key issuedby a trusted third party, the key and a file ciphertext are outsourced to the cloud on the premise of guaranteeing safety; and the user creates a cloud file multi-copy association table, and utilizesa Merkle hash verification tree and a cloud data integrity verification and correlation deletion strategy combined with a user pre-designated random deletion sequence. According to the method and thesystem, the management expenditure of the user on a large number of file keys in a traditional encryption scheme is eliminated, the use convenience degree of the user about cloud ciphertext data is improved, a problem of safe backup of user outsourcing data is solved, and the integrity verification and association deletion requirements of the cloud multi-copy data by the user are met.