A packet transmission method, device, and system for network technologies are disclosed. A first network device receives, by using a first VPLS instance a packet to be sent to a user-side device connected to the second network device. The first network device forwards, based on an association relationship between the first VPLS instance and the first VPWS instance, the packet to a second VPWS instance in the second network device by using the first VPWS instance. A VPLS instance is associated with a VPWS instance in the first network device. A packet that is received by using the VPLS instance and that is to be sent to a user-side device can be forwarded by using the associated VPWS instance, so that pressure to learn a MAC address for packet transmission is reduced, and forwarding performance of the system is ensured.