Embodiments of the present invention disclose a method for processing a host route in a virtual subnet, a related device and a communications system. The method for processing a host route in the virtual subnet includes: receiving, by a first provider edge device, a packet for address resolution, where a virtual subnet site in which the first provider edge device is located further includes at least one second provider edge device; determining, by the first provider edge device, whether a source MAC address carried in the packet is a virtual MAC address; and when it is determined that the source MAC address is a virtual MAC address, skipping performing at least one of the following operations: saving a local CE host routing table entry corresponding to a source IP address carried in the packet, or distributing, in the virtual subnet based on a routing protocol of a layer 3 VPN, a local CE host route corresponding to the IP address. Technical solutions of the embodiments of the present invention are helpful to avoid forming a CE host routing loop to a greatest extent, further improving efficiency of data packet transmission between CE hosts.