The invention proposes an SDN broadcast processing method based on ARP event triggering agent. In this method, the controller is used as an agent to process ARP broadcast packets, and the storage mode of host state information, host information initialization, and host information real-time update mechanism are proposed to ensure that once a host is successfully connected to the network, it will be perceived, and any behavior of the host will cause its state Changes in information can update the host status information in time to ensure the integrity and real-time performance of host information. As a real-time ARP broadcast packet processing strategy, the present invention is applicable to other network models with centralized control characteristics, and the method has the advantages of reducing data plane traffic, reducing control plane traffic, reducing controller load, reducing host end load, and the like.