This application provides a data transmission method and communications apparatus, to improve transmission efficiency. The method may include obtaining, by a MAC entity of a first communications device from an upper layer, first data on each of at least one first logical channel and second data on each of at least one second logical channel, where a service type or a destination address of the first data is different from a service type or a destination address of the second data. The method may also include generating, by the first communications device, a MAC PDU, where the MAC PDU includes the first data on each first logical channel and the second data on each second logical channel; and sending, by the first communications device, the MAC PDU through a direct link.