The invention discloses an SDN (Software Defined Network)-based ARP (Address Resolution Protocol) proxy realizing method, which comprises the following steps: receiving an ARP request message sent bya traditional network switchboard; inquiring whether a flow table responding to the ARP request message is stored or not; if YES, making a response to the ARP request message according to the flow table; if NO, uploading the ARP request message to an SDN controller; and receiving an ARP response message sent by the SDN controller, and sending the ARP response message to traditional network equipment. The method realizes control of OpenFlow equipment through a control plane to complete simulation of an ARP protocol, so that the traditional network equipment can realize communication with OpenFlow within an expectation; and meanwhile, by centralized management of the OpenFlow network equipment, extra increase of a maintenance workload is not required under a condition of not supporting the ARP protocol.