The utility model provides a method and a device to update a plurality of port addresses in an address resolution protocol (ARP) table, which is characterized in that when a media access control (MAC) migration is initiated by a port migration, a detected port address and a corresponding MAC address after the port migration are obtained during the MAC migration; a port address in the ARP table, corresponding to the detected MAC address, is updated to be the detected port address. The utility model has the advantages that the switch does not need to wait until the ARP ages so that the fast update of the port addresses in the ARP table is realized and that the third layer forwarding not correctly carrying on in a long time during the port migration is avoided.