Objective：To investigate the role and possible molecular mechanism of microRNA（miR）-558 in liver cancer. Methods：RT-PCR was used to detect the expression of miR-558 in 35 liver cancer tissues and 35 paracancerous tissues. The effects of miR-558 and TNFAIP1 on the growth and cycle of hepatoma cell were detected by cell counting kit-8（CCK-8），plate clone and flow cytometry. Luciferase assays were performed to analyze the relationship between miR-558 and TNFAIP1. The expression of protein level was detected by Western blot. Results：The expression of miR-558 in the liver cancer tissues was significantly higher than that in the paracancerous tissue（P < 0.01）. Knock down of miR-558 significantly inhibited the proliferation of hepatoma cells，while overexpression of miR-558 could significantly promote the growth of hepatoma cells（P < 0.01）. MiR-558 functioned in hepatoma cells through targeting TNFAIP1 directly. TNFAIP1 overexpression could significantly reverse the effect of miR-558 on hepatoma cell. Conclusion：MiR-558 was highly expressed in liver cancer tissue，and miR-558 can promote the proliferation of hepatoma cells by targeting TNFAIP1. MiR-558 had a certain value of target therapy in liver cancer patients.