Abstract: Objective To explore the application value of preemptive analgesia with dexmedetomidin in the operation of upper limb fracture. Methods A total of 106 patients with upper limb fractures who underwent surgical treatment between March, 2015 and June, 2017 were selected as the subjects. They were randomly divided into control group and observation group with 53 cases in each group. The two groups were treated by general anesthesia with tracheal intubation. The control group was injected with isodose saline for 10 min before anesthesia, while the observation group pumped 0.5 g/kg right Dexmedetomidine for 10min before anesthesia and intraoperative pump injection right beauty pyrimidine 0.3 μg/kg, and the hemodynamic parameters at 15 min before operation(T₁), 3 h after operation(T₂), 6 h after operation(T₃) and 12 h after operation(T₄), pain degree at T₂, T₃ and T₄, and the adverse reactions were observed. Results At T₁, there was no significant difference in hemodynamic indexes between the two groups (P>0.05), There was no significant difference of MAP and HR between the T₂, T₃, T₄ and T₁ in the observation group (P>0.05). At T₂, T₃ and T₄, MAP and HR in the control group were significantly higher than those in the observation group, and the difference was statistically significant (P<0.05). At T₂, T₃ and T₄, VAS score of the observation group was significantly lower than that of the control group. The number of times of postoperative patient-controlled analgesia pump was significantly less than that of the control group (P<0.05). The incidence of adverse reactions in the observation group was 9.43%, compared with 24.53% in the control group, the difference was statistically significant (P<0.05), and no serious adverse reactions occurred in the two groups. Conclusion The application of Dexmedetomidine preemptive analgesia in patients with upper limb fracture surgery can effectively reduce postoperative pain, maintain hemodynamic stability and reduce the dosage of postoperative patient-controlled intravenous analgesia, and it is safe and worthy of promotion.