A data transmission method, wherein the method applies to an Ethernet interface and the method comprises: performing, at a reconciliation sublayer, RS, of a transmit end device, grouping processing on at least one piece of media access control, MAC, layer data that comes from a MAC layer, or adding a group identifier at the MAC layer or at a layer above the MAC layer, to determine at least one MAC layer data group; allocating, at the RS or a physical coding sublayer, PCS, of the transmit end device, according to target bandwidth required by a target MAC layer data group and preset reference bandwidth of a logical channel, multiple logical channels from N logical channels to the target MAC layer data group, so that the allocated multiple logical channels correspond to only the target MAC layer data group, wherein multiple logical channels are multiplexed to one physical channel; performing, at the PCS of the transmit end device, encoding processing on the target MAC layer data group according to the allocated multiple logical channels to generate target physical layer data, wherein the allocated multiple logical channels correspond to only the target physical layer data; and sending, at a physical medium dependent sublayer, PMD, of the transmit end device, the target physical layer data and first indication information to a target receive end device of at least one receive end device through one or more physical channels into which the multiple logical channels are multiplexed, wherein the first indication information specifies a mapping relationship between the target MAC layer data group and the allocated multiple logical channels. performing, at a reconciliation sublayer, RS, of a transmit end device, grouping processing on at least one piece of media access control, MAC, layer data that comes from a MAC layer, or adding a group identifier at the MAC layer or at a layer above the MAC layer, to determine at least one MAC layer data group; allocating, at the RS or a physical coding sublayer, PCS, of the transmit end device, according to target bandwidth required by a target MAC layer data group and preset reference bandwidth of a logical channel, multiple logical channels from N logical channels to the target MAC layer data group, so that the allocated multiple logical channels correspond to only the target MAC layer data group, wherein multiple logical channels are multiplexed to one physical channel; performing, at the PCS of the transmit end device, encoding processing on the target MAC layer data group according to the allocated multiple logical channels to generate target physical layer data, wherein the allocated multiple logical channels correspond to only the target physical layer data; and sending, at a physical medium dependent sublayer, PMD, of the transmit end device, the target physical layer data and first indication information to a target receive end device of at least one receive end device through one or more physical channels into which the multiple logical channels are multiplexed, wherein the first indication information specifies a mapping relationship between the target MAC layer data group and the allocated multiple logical channels.