Abstract: [Objective] To introduce the surgical technique and preliminary clinical results of injury of medial retinaculum attachment to patella by reconstructed and repaired technique under arthroscopy. [Method] From May 2015 to September 2019, 30 patients underwent arthroscopic repair of primary acute patellar dislocation. The decortication of the cartilaginous free body was explored under the arthroscope, and the free body was removed if necessary. Insertion of thread anchor into the medial edge of the patella. The medial edge of the parallel patella was punctured equally from skin to the articular cavity by the lumbar puncture needle. The high-strength thread was introduced to form a noose, which led the anchor suture out of the skin. Use the probe hook to hook out the sutures through the skin at the place where the anchor was placed, tighten the knot in advance, loosen the lateral retinaculum moderately according to the patellar track, and finally tie the knot to lock the suture. [Results] All the 30 patients were followed up. In the last follow-up, the range of motion of the knee joint was normal, no recurrent patellar dislocation, no obvious joint stiffness and dysfunction. The Lysholm score improved from (58.10±8.41) preoperation to (81.33±5.30) at 6 months postoperative and (92.17 ±5.19) at the last follow-up. The patellar tilt angle(PTA) and congruence angle(CA) were improved from (23.20±2.98)°and (8.13±2.90)°preoperation to (10.40±1.90)°and (-7.30±1.32)°at the last follow-up, the differences were statistically significant (P＜0.05). [Conclusion] The injury of medial retinaculum attachment to patella by reconstructed and repaired technique under arthroscopy for APD with injury of medial patellar retinaculum attachment to patella can restore the stability and function of patellofemoral joint, so it is an effective treatment.