Embodiments of the present disclosure provide a data transmission method and device. The method comprises: monitoring PSCCHs in each slot within a slot set separately, to detect whether exists a PSCCH transmitted from a second terminal targeting to the first terminal in each slot within a slot set (S202); receiving an associated PSSCH based on each detected PSCCH targeting to the first terminal (S204); and transmitting one PSFCH carrying a HARQ feedback corresponding to each slot within the slot set in a slot corresponding to the slot set; wherein, the slot set comprises one or more slots (S206).