Objective: To evaluate operative effects of a new method to reconstruct anterior crucial ligament (ACL) and posterior crucial ligament (PCL) simultaneously by using patellar tendon under arthroscopy.Methods: From November 1999 to November 2003,the injured ACL and PCL of 11 patients were fixated with compressed screws and reconstructed under arthroscopy with the bone-patellar tendon-bone treated with deep hypothermia and T radiation. At the same time, 2 patients were treated with medial collateral ligament (MCL)reconstruction, 3 with lateral collateral ligament (LCL)reconstruction, 1 with meniscus suture and 4 with whole or partial resection.Results: All patients were followed up for 12-26months (average 16.5 months ). The Lysholm score method was employed to evaluate the knee function. The average preoperative score was 45.3 and the postoperative score was 86.4. Anterior drawer test (ADT) was positive in 11 knees preoperatively and feeble positive in one knee postoperatively. Lachman test was positive in 11 knees preoperatively and in one postoperatively, and feebly positive in two postoperatively. Posterior drawer test was positive in 11 knees preoperatively and feebly positive in 2postoperatively. There were 2 knees with tolerable pain and 2 with knee flexion of 5°-20°.Conclusions: As for simultaneous reconstruction of ACL and PCL under arthroscopy, ailogeneic bone-patellar tendon-bone can not only avoid injury and complication caused by autografting, but also help rehabilitation of the knee function.