The embodiments discloses a data transmission method and device. The method includes: separately configuring, by an eNodeB in different time units on a specific frequency band according to a TDD mode or an FDD mode, an uplink frequency resource used for transmitting uplink data and a downlink frequency resource used for transmitting downlink data; and sending, by the eNodeB, downlink data to user equipment UE by using the configured downlink frequency resource, and receiving, by using the configured uplink frequency resource, uplink data sent by the UE, so that an uplink frequency resource and a downlink frequency resource are configured in different time units on a same frequency band according to both a TDD mode and an FDD mode.