The present invention proposes a Provable Data Integrity (PDI) verifying method, in which data are firstly fingerprinted at a client, and the fingerprints are sent to an archive along with the data; when necessary, the client sends a “challenge” to the archive so as to determine the integrity of the data, and the archive proves the integrity of the data by using the received fingerprints; and finally, the client verifies the integrity of the data based on the output from the archive in response to the “challenge”.