Abstract: Objective To observe the effect of ultrasound-guided interscalene brachial plexus block with low concentration ropivacaine in patients with operation of upper limb fracture. Methods Totally 91 patients with operation of upper limb fracture were selected and divided into two groups according to alternate grouping method. All the patients were anesthetized with intermuscular brachial plexus block of ropivacaine under the guidance of ultrasound. Control group(n=45)was given 0.5% ropivacaine for anesthesia block, and observation group(n=46)was given 0.25% ropivacaine for anesthesia block. The condition of nerve block, anesthesia related indexes and adverse reactions were compared between the two groups at 30 minutes after anaesthetization. Results There was no significant difference in the ratio of patients with complete blocks of radial nerve, ulnar nerve, median nerve and musculocutaneous nerve between the two groups at 30 minutes after medication use(P>0.05). The duration of analgesia and recovery time of motor block in the observation group were significantly shorter than those in the control group(P<0.05). The incidence of anesthesia related adverse reactions in the observation group was 4.35%, which was significantly lower than 20.00% in the control group(P<0.05). Conclusion Ultrasound-guided interscalene brachial plexus block with low concentration ropivacaine is effective in treatment of patients with operation of upper limb fracture, which can meet the needs of surgery and cause less adverse reactions.