A network emulation device and method in a terminal of an IEEE 802.16 communication system supporting IPv6 communications based on a Neighbor Discovery (ND) protocol are provided. The terminal includes an IPv6 module for performing an ND mechanism to search for a neighbor terminal or a router, a MAC module for communicating based on the IEE 802.16 standard, and a network emulation module provided between the IPv6 module and the MAC module for analyzing a ND message received from the IPv6 module and discarding the ND message or generating a response message for the ND message according to the message type. The network emulation module converts a broadcast ND message to a unicast message and provides the unicast message to a corresponding network device if network information needed to internally generate the response message is not collected.