The invention discloses a processing method of connecting a switch with Ethernet that has three layers directly to a host computer route, which is used for preventing a data packet whose aim IP is an IP address of the host computer from being washed into a CPU If the switch with Ethernet that has three layers has an ARP of a directly connected host computer but has no MAC of the computer host, comprising the following procedures: (a) a switch receives an address resolving protocol (APR) packet delivered by certain equipment, learns APR information from the APR packet and get a corresponding media access control (MAC) address according to the IP address in the APR information; (b) the switch searches a MAC table on the MAC address according to the MAC address, if the MAC address of the equipment can not be learned, then a direct route of the IP address is added, so as to lead the switch desert the information when the information is transmitted by the switch through the directly connected route. By adopting this method, the operation of the switch is not affected when the CPU can not process other packets.