Abstract: Objective To evaluate the efficacy of thymosin ɑ1 combined with arsenic trioxide in the treatment of advanced primary liver cancer( PLC). Methods A total of 59 patients with advanced PLC who were admitted to Jiangyan Hospital of Traditional Chinese Medicine from July 2011 to July 2014 were divided into two groups: control group and combination therapy group. The two groups were given symptomatic and supportive treatment to protect the liver. In addition,29 cases in the control group were treated with arsenic trioxide,while 30 cases in the combination therapy group were administrated with thymosin ɑ1 combined with arsenic trioxide. Comparison of continuous data between the two groups was made by independent- samples t test,and comparison of categorical data was made by chi- square test. Results There was a significant difference in clinical benefit rate between the control group and the combination therapy group( 37. 9% vs66. 7%,χ2= 4. 88,P < 0. 05). The combination therapy group had significantly higher improvement rate of the quality of life( 63. 3% vs37. 9%,χ2= 3. 81,P < 0. 05) and the pain remission rate( 76. 7% vs 44. 8%,χ2= 6. 28,P < 0. 05) than the control group. The levels of alpha fetal protein,carcinoembryonic antigen,carbohydrate antigen 199,and gamma glutamyl transpeptidase decreased in both groups,and the combination therapy group had significantly higher decreases in these indices than the control group( P < 0. 05). The combination therapy group had significantly increased percentages of CD3+and CD4+T cells and CD4+/ CD8+ratio( P < 0. 05) and a significantly reduced percentage of CD8+T cells( P < 0. 01) after treatment. However,there was no significant difference in toxic or side effects between the two groups. Conclusion For patients with advanced PLC,the combination of thymosin ɑ1 and arsenic trioxide can improve the quality of life and the immune function of patients,and no obvious toxic or side effects are found. So it holds promise for clinical application.