A method, a system, and an apparatus for implementing a layer-2 virtual private network (L2VPN) between autonomous systems (ASs) are disclosed. The method includes: receiving a first L2VPN mapping packet from a first AS; parsing the first L2VPN mapping packet to obtain a first label carried in the first L2VPN mapping packet, applying for a second label which is different from the first label carried in the first L2VPN mapping packet, and generating a second L2VPN mapping packet according to the second label; and sending the second L2VPN mapping packet to a second AS. When multiple VPN users need to establish a multi-protocol label switching (MPLS) L2VPN between ASs, the MPLS L2VPN can be established between ASs through the technical solution under the present invention as long as a link exists between the ASs, thus providing high extensibility, high security, and convenient management of the inter-AS L2VPN.