Abstract: [Abstract] Objective Observe the clinical effect of dezocine combined with different dosage of dexmedetomidine for postoperative intravenous analgesia. Method Formulas of 120 cases of laparotomy which were under general anesthesia in the same induction and maintenance process and randomized into four groups were as follows: Group D1: dezocine 0.6mg/kg + Dexmedetomidine 0.045μg/(kg?h) + droperidol 5mg; Group D2: dezocine 0.6mg/kg + Dexmedetomidine 0.1μg/(kg?h) + droperidol 5mg; Group D3: dezocine 0.6mg/kg+ Dexmedetomidine 0.15μg/(kg?h) + droperidol 5mg; Group F: dezocine 0.6mg/kg+ fentanyl 10μg/kg + droperidol 5mg, all diluted into 100ml with normal saline. The background infusion rate was 2ml/h, PCIA dose 0.5ml, and lock time 15min. Outcome measures Pain score of patients at 1, 3, 6, 12, 24, 36 and 48h postoperativly, postoerative sedation scale and postoperative comfort score (BCS) at 24h and adverse reactions, e.g. nausea and vomiting, dizziness, itchy skin, respiratory depression, bradycardia, hypotension muscle rigidity and stupor. Results VAS scores in all group and at all time point were less than 4. The VAS scores of Group D1 at 3, 6, 12 and 24h postoperativly were greater than those of the other 3 groups (P<0.01). BCS scores of all groups were greater than 2. The BCS score of group D1 was less than the other 3 groups (P<0.001). The 24h postoperative sedation score of group D3 was notably higher than those of the other three groups (P<0.001). The incidence rate of nausea and vomiting and EPS (extrapyramidal symptoms) of group F was notably higher than those of the other groups (P<0.05).The incidence rate of bradyarrhythmia of group D3 was higher than those of the other three groups (P<0.05). Conclusion It is effective and has less adverse effects to use Dezocine mixed with a basal infution of 0.1μg/(kg?h) of dexmedetomidine for postoperative analgesia.