Cruciate ligament injury is a common sports injury of the knee joint, common in the process of jumping and landing knee sprain, the injury can feel a sense of joint misalignment, sometimes can also hear a pop, after the injury due to intra-articular bleeding will appear obvious joint swelling, according to statistics, knee sprain with intra-articular hematoma, the incidence of anterior cruciate ligament injury will be as high as 70%. After the injury, the patient has limited joint movement and difficulty walking. If we use four key words to summarize the clinical manifestations of ACL injury in the acute phase, it is “loud, painful, swollen, and limited”. ACL injuries may also be associated with meniscal and/or collateral ligament injuries, which may have other combined clinical manifestations. In the acute phase, if the joint is significantly swollen and painful, ice may be applied and the injury may be diagnosed and treated at a hospital as soon as possible. Current hospital examination technology is very convenient for diagnosing ACL injuries. Knee MRI can clearly visualize the ACL, as well as observe damage to the meniscus and articular cartilage. ACL injuries are usually treated surgically as long as they are above II°. Conservative treatment is only indicated for older patients with partial ACL tears but low sporting requirements. It includes rest, ice, brace braking and functional rehabilitation. The treatment process consists of two steps: the first step aims to eliminate the inflammatory response and restore joint mobility and muscle control. Ice is usually used to reduce pain and swelling, and joint mobility and patellar movement can be started immediately, along with muscle strength training to avoid muscle atrophy. The second step can be started once the patient returns to normal gait. The second step emphasizes N-cord and quadriceps strength training, with open and closed chain exercises. Balance training and proprioceptive training are then performed. Conservative treatment should use a functional brace, which provides full range of knee stability and allows a range of motion for patients with ACL injuries.