[Objective] To investigate the role of miR-199a-3p on mouse skin scar fibroblasts and the potential target of miR-199a-3p. [Methods] A mouse skin keloid model was established. The mRNA levels of miR-199a-3p, Smad1 and keloid related genes in keloid tissues and normal skin tissues were detected by Real-time quantitative PCR. C57BL/6 mouse skin fibroblasts were isolated and cultured for the cellular experimental study. miR-199a-3p mimic and Smad1 siRNA matter were transiently transfected into mouse skin fibroblasts by liposome reagent. the interaction between miR-199a-3p and the 3′-UTR of Smad1 was confirmed by the dual luciferase reporter assay. The expressions of Smad1 and keloid-related genes at mRNA and protein levels after transfection of miR-199a-3p mimic were determined. The expressions of Smad1 and keloid-related genes at protein level after transfection of miR-199a-3p mimic and Smad1 siRNA were determined by Western blot assay. [Results] Compared with normal skin tissues, the expressions of Smad1 (t=-4.403, P=0.010) and keloid related genes, Col1a1(t=-3.334, P=0.016), Col3a1(t=-5.927, P=0.001) and ACTA2(t=-3.673, P=0.010), were significantly increased in keloid tissues, while miR-199a-3p (t=7.059, P<0.001) expression was significantly decreased. Over-expression of miR-199a-3p could significantly decrease the expressions of keloid-related genes, Col1a1 (t=5.514, P=0.005), Col3a1 (t=5.132, P=0.014) and ACTA2 (t=4.136, P=0.026), in mouse skin fibroblasts. Moreover, the dual luciferase reporter assay revealed that miR-199a-3p could interact with the 3′-UTR of Smad1. miR-199a-3p was observed to inhibit Smad1 at mRNA expression level (t=3.556, P=0.024), and at the post-transcriptional level (t=3.781, P=0.019). Meanwhile, miR-199a-3p mimic, in parallel to Smad1 siRNA, decreased the expressions of keloid-related genes, Col1a1 (F=18.804; P=0.003, 0.022), Col3a1 (F=33.212; P=0.001, 0.001) and α-SMA (F=10.181; P=0.020, 0.028), and decreased the proliferation of skin fibroblasts (F=18.622; P=<0.001, <0.001). [Conclusion] miR-199a-3p inhibits the formation of keloid by targeting Smad1.