It manifests as contracture and shortening due to fibrosis of the sternocleidomastoid muscle, but the cause is still unclear and may be related to the following factors: (1) Injury during delivery, one side of the sternocleidomastoid muscle bleeds due to birth injury, forming a hematoma and then mechanizing and contracting. (2) Intrauterine fetal malposition, which causes excessive pressure on one side of the sternocleidomastoid muscle, resulting in local ischemia, followed by excessive degeneration and replacement by fibrous connective tissue. (3) Aseptic inflammation caused by birth injury, resulting in degeneration and scarring of the muscle, and the formation of oblique neck. (4) Acute obstruction of the internal sternocleidomastoid vein at birth. In these children, an olive-like mass, hard and located on the sternocleidomastoid muscle, can be palpated during the first to second month of life and gradually becomes smaller or disappears within 2 to 6 months thereafter, with the right side being more common than the left. This disease needs to be differentiated from the following diseases: 1. congenital cervical spine deformity Short and thick neck, reduced mobility, commonly cervical hemivertebrae, cervical fusion, etc. 2. cervical subluxation Mostly in children aged 3 to 5 years old, soft tissue congestion around the cervical spine caused by inflammation of the pharynx suddenly appears with head and neck deviation, restricted movement, and tension in the collar muscles. Cervical 1 to 2 subluxations can be seen in frontal and lateral cervical spine opening films. 3.Ophthalmologic disease Children with myopia on one side and hyperopia on the other side may have head and neck tilt to one side. However, there is no contracture of the sternocleidomastoid muscle and no restriction of head and neck rotation.4. Other cervical disc lesions, spinal cord space disease, and deficiency of the sternocleidomastoid muscle on one side can cause head and neck tilt. In addition, it should be distinguished from enlarged lymph nodes in the neck, lymphoma, cervical dermatome cyst, carotid body aneurysm and other soft tissue tumors. 1. Conservative treatment During infancy, the child’s neck can be passively stretched by Chinese medicine massage or by parents under the guidance of physicians, pulling the head to the healthy side and turning the jaw to the affected side, with gentle and slow movements. 2. Surgery The best time to operate for children with ineffective or untreated conservative treatment is around 1~1.5 years old, when the child’s face has not yet started to deform significantly, and the face is not affected after surgery, while children of older age have heavier secondary deformities and facial deformation cannot be improved well. Surgical methods: (1) Sternocleidomastoid muscle release: within 5 years of age, the head of the clavicle and the head of the sternum can be cut off and released, more than six years old need to do additional mastoid head release (2) Sternocleidomastoid muscle Z-shaped lengthening In order to make the patient’s postoperative neck appearance beautiful, some scholars in recent years have adopted the “Z” shaped lengthening of the sternocleidomastoid muscle. Postoperative treatment: small children can be fixed with a neck collar for 1~3 months and supplemented with passive head and neck exercises, while those over 6 years old should have their heads fixed in the overcorrected position with a cast for 4~6 weeks and insist on daily passive head and neck exercises after removal of the cast.