Objective: Supracondylar humeral fracture is the most common fracture in children. Currently there are a large number of studies on supracondylar humeral fractures addressing the epidemiology of supracondylar fractures, injury mechanisms, treatments and complications, however there are few studies on how to control the pain in children after fractures and operation. Therefore, we retrospectively analyzed the effectiveness of an intra-articular injection of 0.25% bupivacaine on pain control after CRPP of supracondylar humeral fractures in children. To our knowledge, this is the largest study on the use of an intra-articular injection for pain control after surgery for supracondylar humeral fractures.Methods: This clinical trial was designed to evaluate the efficacy of intra-articular injection of 0.25% bupivacaine as a postoperative pain control in children with supracondylar humeral fractures who underwent closed reduction and percutaneous pinning (CRPP).Subjects (n = 120) were randomized to treatment with 0.25% bupivacaine (treatment group) (n = 60) or no injection (control group) (n =71). After surgery, all patients were prescribed Ibuprofen for analgesia. The Ibuprofen doses and the times of administration were recorded. The Faces Pain Scale-Revised (FPS-R) scores were blindly recorded during postoperative day 1.Results: The results suggested that the use of intra-articular injection of 0.25% bupivacaine improved pain control and decreased the need for Ibuprofen on postoperative day 1. FPS-R scores were also significantly lower in the treatment group as compared with those of the control group. No intra-articular injection-associated complications were reported. Conclusion: Therefore, the intra-articular injection of bupivacaine significantly improves postoperative pain control following CRPP of supracondylar humeral fractures in children.