【Abstract】 Objective To evaluate the effect and safety of patient-controlled intravenous analgesia (PCIA) with different dosages of dezocine after abdominal operation. Methods 60 patients (ASAⅠorⅡ) undergoing abdominal operation were randomly divided into three groups of A, B, and C with 20 cases each. Patients were intravenously injected with a loading dose of 0.12mg/kg dezocine 20 min before the end of surgery. 0.012, 0.014, and 0.016 mg/(kg•h) of dezocine with 10 mg azasetron were diluted into 100 ml with normal saline in group A, B, and C, respectively. The analgesic effects, analgesic drug consumption , the number of total demand and the number of successfully delivered doses, as well as the side effects, were recorded during the first 48 h after surgery. Results Within 48 h after surgery, VAS scores, analgesic drug consumption, the number of total demand and the number of successfully delivered doses were lower in group C than that of group A and B (P<0.05). There is no difference on the incidence of adverse effects among three groups. Conclusion Patient-controlled intravenous analgesic effect of 0.016mg/(kg•h) dezocine is superior than the lower dosage but with no additional side effects.