Objective To investigate the effectiveness of Kirschner wire combined with silk tension band in the treatment of ulnar collateral ligament avulsion fracture of the thumb metacarpophalangeal joint. Methods Between September 2008 and October 2011, 14 patients with ulnar collateral ligament avulsion fracture of the thumb metacarpophalangeal joint were treated using a combination of Kirschner wire and silk tension band. There were 8 males and 6 females, aged 23-55 years (mean, 40.8 years). The causes of injury were machinery twist injury in 5 cases, manual twist injury in 4 cases, falling in 4 cases, sports injury in 1 case. The time from injury to operation was 2 hours-14 days. All the patients presented pain over the ulnar aspect of the metacarpophalangeal joint of the thumb, limitation of motion, and joint instability with pinch and grip. The lateral stress testing of the metacarpophalangeal joint was positive. Function training was given at 2 weeks after operation. Results All incisions healed by first intention. The lateral stress testing of the metacarpophalangeal joint was negative. All the patients were followed up 6-18 months (mean, 13.1 months). The X-ray films showed good fracture reduction and healing with an average time of 7 weeks (range, 4-10 weeks). At last follow-up, the thumbs had stable flexion and extension of the metacarpophalangeal joint, normal opposition function and grip and pinch strengths. According to Saetta et al. criteria for functional assessment, the results were excellent in 11 cases and good in 3 cases; the excellent and good rate was 100%. Conclusion It is an easy and simple method to treat ulnar collateral ligament avulsion fracture of the thumb metacarpophalangeal joint using Kirschner wire combined with silk tension band, which can meet the good finger function.