A computer-implemented method comprising: determining, by a storage device, a data storage instruction, wherein the data storage instruction carries an identifier and data to be stored; determining, by the storage device and based on the identifier, a blockchain that corresponds to the identifier and a key pair that corresponds to the identifier; storing, by the storage device, the data to be stored in the blockchain based on the key pair; and accessing, by a query device, data that corresponds to the identifier by accessing the blockchain that corresponds to the identifier, wherein determining a blockchain that corresponds to the identifier and a key pair that corresponds to the identifier comprises: determining whether a blockchain that corresponds to the identifier exists in a blockchain network storage node based on a pre-stored mapping relationship between the identifier and each of the key pair and the blockchain; in response to determining that the blockchain that corresponds to the identifier exists in the blockchain network storage node, determining a blockchain that corresponds to the identifier and a key pair that corresponds to the identifier in the blockchain network storage node; and in response to determining that the blockchain that corresponds to the identifier does not exist in the blockchain network storage node, generating a blockchain that corresponds to the identifier and a key pair that corresponds to the identifier. determining, by a storage device, a data storage instruction, wherein the data storage instruction carries an identifier and data to be stored; determining, by the storage device and based on the identifier, a blockchain that corresponds to the identifier and a key pair that corresponds to the identifier; storing, by the storage device, the data to be stored in the blockchain based on the key pair; and accessing, by a query device, data that corresponds to the identifier by accessing the blockchain that corresponds to the identifier, wherein determining a blockchain that corresponds to the identifier and a key pair that corresponds to the identifier comprises: determining whether a blockchain that corresponds to the identifier exists in a blockchain network storage node based on a pre-stored mapping relationship between the identifier and each of the key pair and the blockchain; in response to determining that the blockchain that corresponds to the identifier exists in the blockchain network storage node, determining a blockchain that corresponds to the identifier and a key pair that corresponds to the identifier in the blockchain network storage node; and in response to determining that the blockchain that corresponds to the identifier does not exist in the blockchain network storage node, generating a blockchain that corresponds to the identifier and a key pair that corresponds to the identifier. determining whether a blockchain that corresponds to the identifier exists in a blockchain network storage node based on a pre-stored mapping relationship between the identifier and each of the key pair and the blockchain; in response to determining that the blockchain that corresponds to the identifier exists in the blockchain network storage node, determining a blockchain that corresponds to the identifier and a key pair that corresponds to the identifier in the blockchain network storage node; and in response to determining that the blockchain that corresponds to the identifier does not exist in the blockchain network storage node, generating a blockchain that corresponds to the identifier and a key pair that corresponds to the identifier.