Non-alcoholic fatty liver disease (NAFLD) is one major chronic liver disease emerging the primarily excessive fat accumulation in the liver. Recent studies have demonstrated that hepatic miRNAs play an important role of NAFLD pathogenesis. Previously we identified up-regulation of miR-126-3p and miR-199a-3p in the patient with NAFLD, but their roles remain unclear. In this study, we investigated the role of miR-126-3p and miR-199a-3p on lipid accumulation in 3T3-L1 adipocytes. Transfection of miR-126-3p and miR-199a-3p enhanced lipid accumulation in 3T3-L1 cells after adipocyte differentiation. Next, we evaluated lipid metabolism-related gene expression by quantitative RT-PCR. MiR-126-3p increased CCAAT/enhancer-binding protein-α (C/EBPα) mRNA expression whereas miR-199a-3p did not affect. Moreover, both miRNAs reduced the expression of hypoxia-inducible factor-1α (HIF-1α) mRNA, predicted target of miRNAs. These results suggested that miR-126-3p and miR-199a-3p promote lipid accumulation in 3T3-L1 adipocytes through regulating HIF-1α and/or C/EBPα mRNA expression.