A method includes: obtaining, by a server storing data in a blockchain ledger, compression point information of the blockchain ledger, in which the compression point information includes identification information of a specified data block, a server digital signature, and a user digital signature, in which the compression point information indicates that a specified portion of the blockchain ledger has passed an integrity verification, and in which the specified portion of the blockchain ledger includes data blocks in the blockchain ledger previous to the specified data block in the blockchain ledger; and compressing data of the specified portion of the blockchain ledger.