Objective To observe the effects of dexamethasone on liver function, serum inflammatory factors and immune function in patients with primary liver cancer after hepatectomy. Methods 89 patient undergoing hepatectomy were randomly divided into the observation group (47 cases) and the control group (42 cases). The control group was given conventional treatment, and the observation group was given additional dexamethasone 10 mg every day for 3 days based on conventional treatment. The differences of liver function (ALT, AST, TBIL, ALP), serum inflammatory factors (TNFα, CRP, IL-6, IL-8), immune function (CD3+, CD4+,CD8+ and CD4+/CD8+) and postoperative morbidity between the two groups were compared. Results There were significant differences of ALT, AST, TBIL, ALP between the two groups (P＜0.05). The levels of ALT, AST and TBIL in the two groups were showed first increasing then decreasing trends with increasing time, but ALP was on the contrary (P＜0.05). The differences of those items in patients between the two groups were statistically different (P＜005). There were significant differences of the levels of TNFα, CRP, IL-8、IL6 in patients between the two groups (P＜0.05). All of those items in the two groups were showed first decreasing then decreasing trend with time (P＜0.05), and the shifting trends of those items in patients between the groups were all statistically different (P＜0.05). There were no significant differences of the CD3+, CD4+, CD8+ and CD4+/CD8+ in patients between the two groups (P＜0.05). CD3+, CD4+ and CD4+/CD8+ of the two groups were presented decreasing trend over time, but CD8+ was on the opposite P＜0.05). The shifting trend of those items in the patients between the two groups were not statistically different (P＞0.05). The intestinal function recovery time and hospitalization time of the observation group were lower than those of the control group, with statistically significant difference (P＜0.05). There were no significant differences in postoperative morbidity between the two groups (P＞0.05). There were no statistically differences of the 1 year and 2 year survival rates in patients between the two groups (P＞0.05). Conclusion The short term and proper application of dexamethasone can play an important role in protecting liver and antiinflammation in patients at the perioperative period of hepatectomy. It also helps to recuperation and dose not obviously increase the immunosuppression and postoperative morbidity.