This application discloses a data transmission method and a communication apparatus. The data transmission method includes: The access network device receives a first data packet from a first terminal device, where the first data packet is associated with a terminal group, the terminal group including the first terminal device. The access network device sends the first data packet to a first routing device for forwarding. The first routing device corresponds to the terminal group. The first routing device stores routing information of one or more respective terminal devices of the terminal group. The routing information is for forwarding the first data packet. Signaling overheads can be reduced by using embodiments of this application.