In current server cluster systems, to implement exchange and transmission of data between server nodes, a method of installing a switch in a cluster server is generally adopted at present, that is, a multi-port switch is installed in the cluster server, and each server node is directly interconnected to the multi-port switch. With the increasing application of server nodes, the demand and dependence on the switch are increasing, and a data exchange method between the server nodes of the cluster server system has become one of key factors affecting the stable and efficient operation of the system. When the switch fails and needs to be replaced, the entire system needs to stop running before the faulty device can be replaced, making it impossible for maintenance of the cluster system without interruption. In view of the problems of low maintenance efficiency and insufficient system cost advantage in the design of data exchange between server nodes of current clustered server systems, by taking key electrical factors such as data network link signal operating characteristics into consideration, the present invention provides a method for exchanging data in a cluster server system. The main technical scheme of the method is: establishing a data exchange control unit having double network ports on each server node of a cluster server system; sequentially cascading adjacent server nodes in the cluster system by using the unit; and transmitting data between different nodes by using encapsulated packet data embedded with an address of a server node. In this way, data exchange between neighboring nodes is realized, and data forwarding between non-neighboring nodes is also realized by forwarding via the data exchange control unit, thereby ensuring the flexibility of the system.