The invention discloses a secret key updating method for cloud storage and an implementation method of a cloud data auditing system, and belongs to the technical field of network security. The secret key updating method for cloud storage comprises the steps that when a cloud user needs to update a secret key, a CA server is requested to generate a new secret key, and a new file label and a new data block label are generated based on a file label and a data block label downloaded from a cloud server, the old secret key and the new secret key at present, are uploaded to the cloud server, and are used for replacing the corresponding old file label and the corresponding old data block label in the cloud server. Meanwhile, the invention further discloses the implementation method of the cloud data auditing system on the basis of zero-knowledge verification. When the cloud user needs to update the secret key, the corresponding file label and the corresponding data block label on the cloud server are updated based on the secret key updating method for cloud storage. The secret key updating method for cloud storage and the implementation method of the cloud data auditing system are used in a cloud network, the communication cost, caused by changing of the secret key, between the cloud server and the cloud user can be remarkably reduced, the calculation cost of the operation that the cloud user calculates the labels again is reduced, and the data privacy can be effectively protected in the auditing process.