Implementations of this specification provide blockchain-based recording and querying methods and apparatuses. An example method includes operations performed by an access gateway, including receiving, from a first service system, user data including a user identifier of a user; transmitting, to an identifier hash system, a first hash request for the user identifier; receiving, from the identifier hash system, a hash digest of the user identifier; replacing the user identifier in the user data with the hash digest of the user identifier, and packaging the user data into a storage transaction; transmitting, to a blockchain, the storage transaction; receiving, from the blockchain, a result of the storage transaction having been performed by a smart contract published by the first service system on the blockchain; and providing, to the first service system, the result of the storage transaction.