An SDN-based method for dynamically preventing MAC address spoofing comprises the steps as follows: connecting interchangers in whole network to an SDN controller, establishing a dynamic network based on the SDN, calculating a forward path of a message in real time according to MAC address information, interchanger port information and network topology information, which are reported by interchangers with the SDN controller, obtaining a corresponding relation of the MAC address and a interchanger port on all interchangers on the forward path, issuing real-time dynamic condition of a binding relation to the interchangers on the forward path via a flow table instruction set with the SDN controller, updating a target MAC address and a port binding relational table on the interchangers and binding the MAC address and the interchanger port. Using an SDN frame to sense forward path and network change of the message, the SDN-based method for dynamically preventing MAC address spoofing of the invention realizes the dynamic binding of the MAC address and the interchanger port so as to prevent the MAC address spoofing in whole network to enable management and configuration of the whole network to be simple and intelligent so as to effectively managing the whole SDN network.