A cluster system self-organizing method including receiving, by a node A in a cluster system, a request message sent by an external node for requesting to join the cluster system, where the node A is one node in the cluster system, the node A and at least one other node in the cluster system mutually have a bidirectional neighbor relationship, and two nodes that have the bidirectional neighbor relationship mutually transmit information, separately determining, by the node A, whether a ratio of a space area that is of the node A and that is allocated in the cluster system to a space area that is of each bidirectional neighbor node of the node A and that is allocated in the cluster system meets a preset relationship, and establishing, by the node A, the bidirectional neighbor relationship with the external node when the preset relationship is met.