Scoliosis is an ancient condition that is still not fully understood despite treatment experience approaching 4,000 years. It is categorized into three groups based on age of onset: infantile idiopathic scoliosis, juvenile idiopathic scoliosis, and adolescent idiopathic scoliosis. Treatment can be simplified to the “3O’s”: (1) observation; (2) orthosis; and (3) operative intervention. And how to choose each treatment is complex. Idiopathic scoliosis in young children is characterized by a left thoracic curve and is common in boys. Evaluation of the rib-vertebral angle of the parietal vertebrae (RVAD) predicts progression; if the RVAD is greater than 20°, progression occurs in 80% of cases. Bracing is the main non-surgical treatment for progressive toddler idiopathic scoliosis and includes the TLSO brace and the Milwaukee brace. Surgical treatment includes anterior release and fusion, and posterior fixation and fusion is considered to be the more reasonable surgical approach, but the most important principle is to delay surgical intervention as much as possible while the spine grows and develops, but uncontrolled progression of scoliosis must be prevented. Specific treatment principles are as follows: (1) scoliosis Cobb angle less than 25°, RVAD angle less than 20°, observation, and regular spinal radiological examination; (2) if the scoliosis is greater than the above mentioned angles, brace treatment should be carried out; (3) if the progression of scoliosis is uncontrollable by conservative treatment, surgical treatment should be carried out. Juvenile idiopathic scoliosis is most common in right thoracic curvature and is common in girls. Because of the high incidence of progression, it is often considered a malignant subtype of juvenile idiopathic scoliosis. The principles of treatment for juvenile idiopathic scoliosis are as follows: (1) scoliosis less than 25°, with regular follow-up imaging; (2) scoliosis between 25° and 40°, with a recommendation for bracing; (3) scoliosis between 20° and 25°, but with rapid progression, with a recommendation for bracing; and (4) structural scoliosis greater than 40°, or any scoliosis greater than 50°, should be treated surgically. Adolescent idiopathic scoliosis The most common type of idiopathic scoliosis. The degree of scoliosis progression is predicted by looking at physiology, skeletal maturity, and scoliosis size. The actual incidence of progression is lower in mature patients with smaller scoliosis and greater in immature patients with larger scoliosis. Treatment is primarily based on the size of the scoliosis, with observation recommended for scoliosis less than 30°; bracing recommended between 30° and 40°; and surgery recommended if the scoliosis is greater than 40°. An error of about 10° between observers should be taken into account, and the decision to treat surgically or to observe should be made on a case-by-case basis.