Communication network IO acquisition expansion method and system

The invention discloses a communication network IO acquisition expansion method and system, the method is applied to a system comprising a head node, an intermediate node and a tail node, the head node, the intermediate node and the tail node are sequentially connected through optical fiber communication, and the method comprises the following steps: the tail node detects whether a request connection instruction is received at preset time intervals; if the request connection instruction is received n times, it is judged that a new node needs to be added, a node adding request is submitted to the head node, and n is a natural number; after receiving the new node adding request, the head node allocates a new node ID to the new node, and data communication is established between the new node and the head node; and the new node sends own node information to the head node, the head node distributes a data space in a data packet after receiving the node information of the new node, and the new node establishes data