A cross-chain transaction method, comprising: receiving, by a node, an association transaction sent by a consensus node of a plurality of consensus nodes of a consensus service network, wherein: the association transaction comprises transaction content of a plurality of transactions, identifiers of a plurality of blockchains on which the plurality of transactions occur, and an identifier of an anchor transaction, the anchor transaction comprises data identifiers of the plurality of transactions, identifiers of a plurality of blockchains on which the plurality of transactions occur, and an identifier of an anchor transaction, the node is any node on a first blockchain, the first blockchain is any blockchain of the plurality of blockchains on which the plurality of transactions occur, and the first blockchain and a second blockchain of the plurality of blockchains comprise: a connection node for generating an anchor request and for generating the association transaction based on the plurality of transactions carrying an association identifier corresponding to the identifier of an anchor transaction, a notary node for generating the anchor transaction corresponding to the anchor request, wherein the connection node and the notary node are common to the first blockchain and the second blockchain; and writing, by the node, a transaction that occurs in the first blockchain into the first blockchain based on the identifiers of the blockchains on which the plurality of transactions occur if determining, based on the identifier of the anchor transaction, that the anchor transaction is a valid transaction; wherein before the node receives the association transaction sent by the consensus node, the method further comprises: receiving, by the node, the anchor transaction sent by the consensus node, and writing the anchor transaction into the first blockchain. receiving, by a node, an association transaction sent by a consensus node of a plurality of consensus nodes of a consensus service network, wherein: the association transaction comprises transaction content of a plurality of transactions, identifiers of a plurality of blockchains on which the plurality of transactions occur, and an identifier of an anchor transaction, the anchor transaction comprises data identifiers of the plurality of transactions, identifiers of a plurality of blockchains on which the plurality of transactions occur, and an identifier of an anchor transaction, the node is any node on a first blockchain, the first blockchain is any blockchain of the plurality of blockchains on which the plurality of transactions occur, and the first blockchain and a second blockchain of the plurality of blockchains comprise: a connection node for generating an anchor request and for generating the association transaction based on the plurality of transactions carrying an association identifier corresponding to the identifier of an anchor transaction, a notary node for generating the anchor transaction corresponding to the anchor request, wherein the connection node and the notary node are common to the first blockchain and the second blockchain; and the association transaction comprises transaction content of a plurality of transactions, identifiers of a plurality of blockchains on which the plurality of transactions occur, and an identifier of an anchor transaction, the anchor transaction comprises data identifiers of the plurality of transactions, identifiers of a plurality of blockchains on which the plurality of transactions occur, and an identifier of an anchor transaction, the node is any node on a first blockchain, the first blockchain is any blockchain of the plurality of blockchains on which the plurality of transactions occur, and the first blockchain and a second blockchain of the plurality of blockchains comprise: a connection node for generating an anchor request and for generating the association transaction based on the plurality of transactions carrying an association identifier corresponding to the identifier of an anchor transaction, a notary node for generating the anchor transaction corresponding to the anchor request, wherein the connection node and the notary node are common to the first blockchain and the second blockchain; and a connection node for generating an anchor request and for generating the association transaction based on the plurality of transactions carrying an association identifier corresponding to the identifier of an anchor transaction, a notary node for generating the anchor transaction corresponding to the anchor request, wherein the connection node and the notary node are common to the first blockchain and the second blockchain; and writing, by the node, a transaction that occurs in the first blockchain into the first blockchain based on the identifiers of the blockchains on which the plurality of transactions occur if determining, based on the identifier of the anchor transaction, that the anchor transaction is a valid transaction; wherein before the node receives the association transaction sent by the consensus node, the method further comprises: receiving, by the node, the anchor transaction sent by the consensus node, and writing the anchor transaction into the first blockchain.