In Basketball, the number of non-contact ACL injuries which has been reported is greater than that of contact ACL injuries. According to report, Knee-in Toe-out posture is the most major causative factors for non-contact ACL injuries during basketball. However, there are other opinions such as the Knee-out Toe-in to be the injury posture, and the specific injury factor is not yet elucidated. The aim of this study is to elucidate the injury mechanism by simulating the strain of ACL. The position of ACL were determinate from 3D knee models which were created from computer tomography images. The knee models were created at 0°-120° flexion. Gradation maps of ACL strain during different posture were made to verify injury posture.