The disclosure provides a method, a device, and a system for implementing multicast forwarding in an Extended VLAN (Virtual Local Area Network) Bridge (EVB), wherein the method includes: the EVB controlling bridge receives a multicast frame and acquires a multicast address from the multicast frame; inquires on a master port and an identifier (ID) of a subgroup corresponding to the multicast address from a first preset mapping table; forwards, when the ID of the corresponding subgroup is an Multicast Identifier (MCID), the multicast frame carrying the MCID to a corresponding Port Extender (PE) assembly via the master port; and the PE assembly distributes the multicast frame to a User Equipment (UE) according to a correspondence between the MCID carried in the multicast frame and a downlink port of the PE assembly.