Autoimmune hepatitis (AIH) is a chronic progressive autoimmune disease characterized by hepatic inflammation. This study aimed to investigate the effect of antagomir-155 on concanavalin A (ConA)-induced AIH, and its possible mechanisms. According to the results, the expression of miR-155 was raised in liver tissues after 48 h exposure to ConA. Treatment with antagomir-155 attenuated ConA-induced liver injury in mice by reducing serum alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase levels. In addition, antagomir-155 significantly alleviated the differentiation of Treg/Th17 cells in the livers of AIH mice, and suppressed Th17-cells-mediated production of pro-inflammatory cytokines IL-17A, IL-23, but not Treg-cells-mediated production of anti-inflammatory cytokine IL-10. Finally, the beneficial effect of antagomir-155 on ConA-induced AIH was abolished by administration of recombinant IL-17A. Our data demonstrated that antagomir-155 treatment could prevent AIH via regulating the differentiation of Treg and Th17 cells, suggesting that microRNA-155 may be an intriguing therapeutic target of AIH.