Anterior cruciate ligament (ACL) tearing is one of the most commonly knee injuries in sports. Most ACL injuries in sports occur because of non-contact mechanisms. A better understanding of non-contact ACL injury characteristics as well as ACL loading and injury mechanisms is critical both for prevention and treatment of non-contact ACL injuries. This review summarized the researches on non-contact ACL injury characteristics, ACL loading and its injury mechanisms. The literatures demonstrated that sagittal plane biomechanical factors showed main affect on ACL loading, such as small knee flexion angle, great posterior ground reaction force, and great quadriceps muscle force. A great posterior ground reaction force is associated with a great quadriceps muscle force, which would cause a great anterior draw force at the proximal end of the tibia. A small knee flexion is associated with a large patella tendon-tibia shaft angle and ACL elevation angle, which would result in great ACL loading Current literature also demonstrates that ACL is not the major structure of bearing knee valgus-varus moment and internal rotation moment loadings. Knee valgus-varus moment and internal rotation moments alone are not likely to be the cause of ACL injuries without medial or lateral colletorial ligament injury as the most of non-contact ACL injuries clinically observed.