A data transferring method, a system and a related network device based on proxy mobile (PM) IPv6, which are used for solving the problem that the existing data transferring scheme based on proxy mobile (PM) IPv6 can't distinguishes and controls the mobile node (MN) data packages according to service flow. The data transferring method includes: after the mobile node (MN) initiates the service flow, a mobile access gateway (MAG) and local mobility anchor (LMA) establishes a bidirectional tunnel by information interaction based on service flow binding; in which, in the process of the bidirectional tunnel establishing, the service is distributed the downlink GRE Key and uplink GRE Key, and the local mobility anchor (LMA) adds service flow identifier of the service flow and the binding relationship of the address information of the mobile node (MN); the mobile access gateway (MAG) and local mobility anchor (LMA) transfers the data packages of the service flow initiated by the mobile node (MN) on the bidirectional tunnel between the mobile access gateway (MAG) and local mobility anchor (LMA) according to the service flow identifier and the binding relationship and the uplink, downlink GRE Key.