An embodiment provides a packet transmission method and apparatus, to resolve a problem that occurs when a packet cannot traverse a NAT device when VTEPs communicate with each other through the NAT device. The method is applied to a VXLAN including a first VTEP, a second VTEP, and a NAT device. The method includes: performing, by the first VTEP, VXLAN encapsulation on a first packet, obtaining a second packet; sending, by the first VTEP, the second packet to the second VTEP through the NAT device; and performing, by the second VTEP, VXLAN decapsulation on the received second packet, to obtain the first packet. The first packet is a packet to be sent by the first VTEP, a destination port number of the second packet is obtained based on a destination IP address of the second packet, and a source port number of the second packet is a preset port number.