The invention provides a method and a terminal for synchronizing data between nodes in a block chain. The method comprises the following steps: broadcasting a block chain update message to a block chain network; receiving a request synchronization message sent by the node receiving the block chain update message in the block chain network according to the block chain update message, wherein the request synchronization message comprises broadband capability information corresponding to the node sending the request synchronization message; and synchronizing data matched with the broadband capability information to a corresponding node. A data synchronization mechanism based on the real-time network transmission capability of the block chain node is realized; the data synchronization efficiency between the nodes in the block chain network is improved, meanwhile, due to the unpredictability and unfixity of the bandwidth capacity of each node in the block chain network, the node for data synchronization and the unpredictability of the data updated by each node are decided, and the data safety and the fairness between the nodes are also ensured.