Abstract: OBJECTIVE To investigate the effect of miR-9a on wound healing in rats, and to elucidate its mechanism. METHODS A rat wound healing model was constructed. The miR-9a expression in skin wound healing tissue was detected at different time points. Overexpression of miR-9a, differences between groups were analyzed by using in situ hybridization experiments, HE staining, immunofluorescence staining, scratch assays, and wound healing experiments. RESULTS Compared with pre-injury, miR-9a expression in skin tissue was significantly increased after 7 d of injury(P<0.001). In the miR-9a overexpressed group, the area of the injured area was significantly reduced(P<0.05 or P<0.001). Compared with the control group, after transfection of miR-9a into keratinocyte HaCat, the number of EdU-positive cells was significantly increased(P<0.001) at 14 d and 21 d after injury, the percentage of wound healing was significantly increased(P<0.01), and the number of migrated cells was significantly increased(P<0.001). CONCLUSION miR-9a promotes wound healing in rat skin by promoting proliferation and migration of keratinocytes.