OBJECTIVE To introduce the surgical procedure and clinical result of microsurgical repair on collateral ligament rupture in the interphalangeal joint using superficial flexor tendon of finger. METHODS From 1987, 23 cases with collateral ligament rupture in the interphalangeal joint were repaired by part of superficial flexor tendon of finger. The initial point of collateral ligament was drilled two holes, 2 to 3 mm in distance, and crossed by steel wire. Then the superficial flexor tendon of finger was crossed under the steel wire and sutured to the terminal point of superficial flexor tendon of finger by 5/0 to 7/0 nontraumatic suture thread to maintain suitable tension, and sutured to collateral ligament by 8/0 nontraumatic suture thread. Extension splint fixation was performed 4 to 6 weeks postoperatively. RESULTS Followed up 3 to 6 months, 15 cases were excellent, 6 cases were better, 2 cases were moderate, and the excellent rate was 91.34% according to Saetta standard. CONCLUSION Microsurgical repair on collateral ligament rupture in the interphalangeal joint using superficial flexor tendon of finger is a convenient and effective surgical method.