This application provides a communication method and a communications apparatus. The communication method includes: receiving, by a core network device a message indicating a first data volume of first data transmitted between a second network device and a terminal device; determining, by the core network device, a total data volume of total data transmitted between a first network device and a core network comprising the core network device or total data transmitted between a second network device and the core network; and determining, by the core network device, a second data volume of second data transmitted between the first network device and the terminal device based on the first data volume and the total data volume, wherein the first data, the second data and the total data are data of a bearer, data of a flow, or data of a session.