A method for improving subscriber access capacity of a broadband access device is disclosed, including: establishing a Virtual Local Area Network Path Identifier (VlanPI) and corresponding VlanPI Tag, establishing a VLAN Circuit identifier (VlanCI) and corresponding VlanCI Tag for each access port of the broadband access device, dividing the access ports into groups and assigning the established VlanPIs to each group; then, before transmitting an ethernet frame, determining the VlanCI which corresponds to the access port and inserting the VlanCI Tag for identifying the VlanCI into the standard ethernet frame, determining the VlanPI corresponding to the group to which the access port belongs and inserting the VlanPI Tag which is used to identify the VlanPI into the standard ethernet frame, and transmitting the ethernet frame to an uplink device through an uplink port by the broadband access device which directly connects with the uplink device.