This application provides a data transmission method. The method includes: A terminal device receives indication information from a network device, where the indication information includes a bit sequence, a value of an ith bit in the bit sequence indicate a usage status of an ith logical channel in M logical channels associated with a radio bearer, and a duplication transmission function is configured for the radio bearer; the terminal device transmits data based on the indication information through at least one logical channel associated with the radio bearer; and because the M logical channels are sorted based on IDs of cell groups associated with the M logical channels and IDs of the M logical channels, the ith bit in the bit sequence included in the indication information indicates the usage status of the ith logical channel in the M logical channels.