A method for preventing MAC address counterfeiting may include: receiving, by an authentication device, a source MAC address and access port information of an access port, wherein the source MAC address and the access port information are associated with an authentication request from the access port; determining, by the authentication device, whether the source MAC address received is a counterfeit MAC address according to the source MAC address received, the access port information received, and access port information that is stored in the authentication device and corresponds to the source MAC address received; and if the source MAC address received is a counterfeit MAC address, rejecting, by the authentication device, the authentication request. A system, an access device and an authentication device are also proposed.