Objective To evaluate effects of sedation and analgesia of dexmedetomidine hydrochloride injection combined with remifentanil during radiofrequency ablation among patients with liver cancer.Methods Sixty patients with liver cancer were equally divided into two groups: the dexmedetomidine hydrochloride injection group treated with dexmedetomidine hydrochloride injection combined with remifentanil and the control group treated with propofol plus remifentanil. The heart rate, blood pressure, respiratory rate, oxygen saturation, observer’s assessment of alertness/sedation(OAA/S), bispectral index of patients were recorded at 15 minutes before local anesthesia(T₀), during local anesthesia(T₁), at the beginning of the operation(T₂), the time radio frequency reached the highest temperature(T₃), at the end of the operation(T₄) and 5 minutes after suspension of medication(T₅). Perioperative adverse reactions and patients’ rate of satisfaction were also recorded.Results The changes of systolic blood pressure, diastolic blood pressure, respiratory rate, oxygen saturation in the dexmedetomidine hydrochloride injection group were significantly different from those of the control group (F=2.496,P=0.033;F=2.658,P=0.025;F=11.900,P=0.000;F=6.378,P=0.000).But the change of heart rate was not significantly different between the two groups (F=0.704,P=0.622). OAA/S in the dexmedetomidine hydrochloride injection group was lower than that of the control group (F=6.978,P=0.000). The bispectral index of the dexmedetomidine hydrochloride injection group was higher than that of the control group (F=519.780,P=0.000).The incidence of respiratory depression, perioperative body movement, nausea and vomiting, and delayed recovery in the dexmedetomidine hydrochloride injection group was lower than in the control group(χ²=15.635,P=0.000、χ²=9.834,P=0.000、χ²=6.613,P=0.013). The rate of patient satisfaction in the dexmedetomidine hydrochloride injection group was higher than that of the control group(χ²=7.938,P=0.000).Conclusions Patients with liver cancer who have received dexmedetomidine hydrochloride injection during radiofrequency ablation can get good sedative and analgesic effect. Patients can be awakened. Anesthesia is safer and more effective.