A data sending method is provided. The method includes: allocating, by a Media Access Control (MAC) entity of a first network node, data packets to at least one hybrid automatic repeat request (HARQ) unit of at least two cells, where the at least two cells use different radio access technologies RATs, the at least two cells share one HARQ unit or each of the at least two cells is corresponding to one HARQ unit, and the HARQ unit is a HARQ entity and/or a HARQ process; and sending, by the first network node, the data packets to a second network node by using the at least two cells. According to the foregoing solution, the data packets are allocated to the at least one HARQ unit of the at least two cells by using a shared MAC layer, so as to effectively reduce an end-to-end delay.