ObjectiveTo investigate the feasibility and effectiveness of absorbable anchor combined with Kirschner wire fixation in the reconstruction of extension function of old mallet finger. MethodsBetween January 2020 and January 2022, 23 cases of old mallet fingers were treated. There were 17 males and 6 females with an average age of 42 years (range, 18-70 years). The cause of injury included sports impact injury in 12 cases, sprain in 9 cases, and previous cut injury in 2 cases. The affected finger included index finger in 4 cases, middle finger in 5 cases, ring finger in 9 cases, and little finger in 5 cases. There were 18 patients of tendinous mallet fingers (Doyle type Ⅰ), 5 patients were only small bone fragments avulsion (Wehbe type ⅠA). The time from injury to operation was 45-120 days, with an average of 67 days. The patients were treated with Kirschner wire to fix the distal interphalangeal joint in a mild back extension position after joint release. The insertion of extensor tendon was reconstructed and fixed with absorbable anchors. After 6 weeks, the Kirschner wire was removed, and the patients started joint flexion and extension training. Results The postoperative follow-up ranged from 4 to 24 months (mean, 9 months). The wounds healed by first intention without complications such as skin necrosis, wound infection, and nail deformity. The distal interphalangeal joint was not stiff, the joint space was good, and there was no complication such as pain and osteoarthritis. At last follow-up, according to Crawford function evaluation standard, 12 cases were excellent, 9 cases were good, 2 cases were fair, and the good and excellent rate was 91.3%. Conclusion Absorbable anchor combined with Kirschner wire fixation can be used to reconstruct the extension function of old mallet finger, which has the advantages of simple operation and less complications.