The present invention discloses a method, apparatus, and system for allocating a label in a seamless multi-protocol label switching network, which greatly reduces the complexity of the access node device, effectively cuts down the operation costs for the operator, and enhances the scalability of the system. The method includes: obtaining label information of a first access node, where the label information comprises the pseudowire PW destination address of the first access node; and sending the label information to a second router by using a BGP message or a T-LDP message so that the second router configures a PW label and/or a flow label of the first access node to a second access node by using the access network configuration protocol according to the label information.