A method for processing a cross-chain transaction in a cross-chain transaction system, wherein the cross-chain transaction system comprises a first node, a second node, and a third node, the first node maintains a first blockchain, the second node maintains the second blockchain, the third node does not maintain the first blockchain and the second blockchain, wherein the cross-chain transaction includes a first transaction and a second transaction, wherein the first and the second transactions are associated with each other, the first transaction belongs to the first blockchain and the second transaction belongs to a second blockchain, wherein the method comprises: determining, by the first node, that a transaction status of the first transaction is a first status, wherein the first status indicates that consensus verification on the transaction succeeds; obtaining, by the first node, a transaction status of the second transaction; and when the transaction status of the second transaction is the first status, modifying, by the first node, target data based on transaction data of the first transaction, wherein the target data is data that is in a status database in the first node and that is related to the first transaction; wherein the obtaining, by the first node, a transaction status of the second transaction comprises: receiving, by the first node, the transaction status that is of the second transaction and that is sent by the third node; wherein the method further comprises: obtaining, by the first node, a first hash of the second transaction through calculation, or receiving the first hash that is of the second transaction and that is sent by a first client, wherein the first client is an initiator of the first transaction; and receiving, by the first node, a second hash that is of the second transaction and that is sent by the third node, wherein if the first hash of the second transaction is equal to the second hash of the second transaction, it indicates that transaction data of the second transaction is correct; and if the first hash of the second transaction is not equal to the second hash of the second transaction, it indicates that the transaction data of the second transaction is incorrect. determining, by the first node, that a transaction status of the first transaction is a first status, wherein the first status indicates that consensus verification on the transaction succeeds; obtaining, by the first node, a transaction status of the second transaction; and when the transaction status of the second transaction is the first status, modifying, by the first node, target data based on transaction data of the first transaction, wherein the target data is data that is in a status database in the first node and that is related to the first transaction; wherein the obtaining, by the first node, a transaction status of the second transaction comprises: receiving, by the first node, the transaction status that is of the second transaction and that is sent by the third node; wherein the method further comprises: obtaining, by the first node, a first hash of the second transaction through calculation, or receiving the first hash that is of the second transaction and that is sent by a first client, wherein the first client is an initiator of the first transaction; and receiving, by the first node, a second hash that is of the second transaction and that is sent by the third node, wherein if the first hash of the second transaction is equal to the second hash of the second transaction, it indicates that transaction data of the second transaction is correct; and if the first hash of the second transaction is not equal to the second hash of the second transaction, it indicates that the transaction data of the second transaction is incorrect. receiving, by the first node, the transaction status that is of the second transaction and that is sent by the third node; wherein the method further comprises: obtaining, by the first node, a first hash of the second transaction through calculation, or receiving the first hash that is of the second transaction and that is sent by a first client, wherein the first client is an initiator of the first transaction; and receiving, by the first node, a second hash that is of the second transaction and that is sent by the third node, wherein if the first hash of the second transaction is equal to the second hash of the second transaction, it indicates that transaction data of the second transaction is correct; and if the first hash of the second transaction is not equal to the second hash of the second transaction, it indicates that the transaction data of the second transaction is incorrect. obtaining, by the first node, a first hash of the second transaction through calculation, or receiving the first hash that is of the second transaction and that is sent by a first client, wherein the first client is an initiator of the first transaction; and receiving, by the first node, a second hash that is of the second transaction and that is sent by the third node, wherein if the first hash of the second transaction is equal to the second hash of the second transaction, it indicates that transaction data of the second transaction is correct; and if the first hash of the second transaction is not equal to the second hash of the second transaction, it indicates that the transaction data of the second transaction is incorrect.