A method for loopback detection includes: receiving a loopback detection frame by a port; detecting and determining whether the loopback detection frame is transmitted via the port; analyzing the loopback detection frame and determining whether a loopback has occurred in a network device when the loopback detection frame is transmitted via the port; when the loopback has occurred, determining the loopback has occurred in which of one or more virtual local area networks (VLANs) that the port joins in; blocking the VLAN(s) that the port transmitting the loopback detection frame joins in and in which the loopback occurred, for the port being unable to transmit any packet in the blocked VLAN(s); and when the loopback has not occurred, dropping the loopback detection frame.