A data transmission method and device relate to the technical field of communications and can effectively improve resource utilization of the system. The data transmission method comprises: a user equipment receiving downlink data sent by a base station through downlink resources of a special subframe (101); the user equipment determining its corresponding guard period level, the guard period level being corresponding to a round-trip time of the user equipment and indicating the length of an orthogonal frequency division multiplexing (OFDM) symbol in a guard period corresponding to the user equipment in the special subframe (102); the user equipment determining, according to its corresponding guard period level, a location of uplink resources corresponding to the user equipment in guard period resources of the special subframe (103); and the user equipment sending uplink data to the base station through the uplink resources corresponding to the user equipment in the guard period resources of the special subframe (104). The embodiments of the present invention can be applied in a wireless communication system.
