Disclosed herein are methods, systems, and apparatus, including computer programs encoded on computer storage media, for blockchain-based hierarchical data storage. One of the methods includes: determining, based on a blockchain stored in a database that includes multiple levels of storage, a block number interval that includes one or more block numbers associated with data nodes to be migrated to a lower level of storage in response to the data nodes meeting a data migration condition, wherein each of the data nodes is included in a state Merkle tree and is associated with a block number of a block of the blockchain where the corresponding data node was last updated, and the lower level of storage corresponds to a storage media with lower storage cost.