Objective To investigate the effect of dexmedetomidine on serum inflammatory reaction and perioperative neurocognitive disorder in elderly patients undergoing laparoscopic radiofrequency ablation of liver cancer. Methods Eighty elderly patients undergoing elective laparoscopic radiofrequency ablation for liver cancer were randomly divided into two groups：dexmedetomidine group（group D）and control group（group C）. Venous blood samples were collected to detect the concentrations of TNF⁃α，IL⁃6，IL⁃10，CRP and CD11b in serum. The cognitive function of the patients in the two groups was evaluated with Mini⁃Mental State Examination（MMSE）and Montreal Cognitive Assessment（MoCA）. Results The levels of serum TNF ⁃α，IL ⁃6，CRP and CD11b in both groups were higher than those before operation，and the level of serum IL ⁃10 in group D was lower than that in group C after radiofrequency ablation（60 min），and the level of serum IL⁃10 in group D was higher than that in group C（P＜0.05）. The incidence of perioperative neurocognitive disorder in group D was lower than that in group C（P＜0.05）. Conclusion Dexmedetomidine could reduce the serum levels of pro ⁃inflammatory factors such as TNF⁃α，IL⁃6，CRP and CD11b in elderly patients undergoing laparoscopic radiofrequency ablation for liver can⁃ cer，reduce the inflammatory reaction and reduce the incidence of perioperative neurocognitive disorder.