Objective To explore the efficiency and effect of self-developed automatic cutting instrument for cutting microskins, and evaluate its effect in repairing full-thickness skin defects of rats. Methods The efficiency and effect of the automatic cutting instrument in preparing microskins were evaluated by comparing with that cut by hand. The microskins prepared by mechanical cutting (experimental group) and manual cutting (control group) were observed by hematoxylin-eosin (H-E) staining, and the tissue activity of the unit mass microskins of the experimental group and the control group was detected by cell counting kit 8 (CCK-8) assay. The microskins of the experimental group and the control group were transplanted into the rat model of full-thickness skin defect at the ratio of 1∶20, and the rate of wound epithelialization was observed. Masson staining, collagen Ⅳ immunofluorescence staining and Ki-67 immunohistochemical staining were used to detect the structure and arrangement of collagen fibers, the formation of basement membrane and the proliferation of wound cells. Results The time required for cutting 2 cm×3 cm skin by using the automatic cutting instrument was 5 min, and the manual cutting time with tissue scissors was about 40 min. The results of H-E staining showed that the microskins in the experimental group had intact structure, but those cut by hand was not, their epidermis was seriously damaged. CCK-8 assay showed that the activity index of skin grafts in the experimental group was significantly higher than that in the control group (［0.067981±0.004467］ mg^-1 vs ［0.045168±0.002698］ mg^-1, P＜0.01). On the 24^th day after transplantation, the rate of wound epithelialization in the experimental group was (78.6±2.3)%, which was significantly higher than that in the control group (［27.2±1.9］%, P＜0.01). Masson staining showed that the thickness of granulation tissue in the experimental group was significantly lower than that in the control group, and the arrangement of collagen was loose and regular. In the experimental group, the wound basement membrane formed well and the basal layer cells proliferated obviously, while in the control group, the basement membrane formed poorly and the basal layer cells did not proliferate obviously. Conclusion The self-developed automatic cutting instrument has the advantages of high efficiency of cutting microskins, intact structure and high tissue activity retention, and can quickly repair the animal model of full-thickness skin defect at 1∶20 amplification ratio. It has different characteristics from that of traditional manual cutting microskins, and has a good application prospect.