Hip dysplasia, also known as congenital hip dislocation, developmental hip dislocation, congenital hip subluxation, and acetabular dysplasia, is a group of diseases that develop in the fetal and neonatal periods due to disorders in the relationship between the femoral head and the acetabulum, and then to varying degrees of hip abnormalities, including acetabular abnormalities, abnormalities of the femoral head and proximal femur, and abnormalities of the hip capsule and soft tissue. The natural course of the disease has a high disability rate and seriously affects the quality of life of patients. In 1991, the American Academy of Orthopaedic Surgery and the North American Academy of Pediatric Orthopaedics recommended that this name be standardized to hip dysplasia. Risk factors for DDH include: first birth, female children, breech babies, whiteness, and the practice of binding the legs of newborns. After a large amount of clinical data and imaging, it is now believed that the critical period for hip developmental contouring is within 6 weeks of the newborn, and the majority of DDH found during this period can develop and correct well with appropriate conservative treatment. The best time for surgical treatment is within 18-24 months for a small number of children with severe disease. Treatment of children older than 8 years of age will become increasingly difficult. The main diagnostic methods and bases vary in different age groups. Physical examination and ultrasound are the mainstay in newborns; physical examination and radiographs in infants and children; older children and adults require more detailed examination due to different surgical options. There are many classifications and typologies of DDH, and the main ones that have been recognized are: Crowe’s classification, Graf’s ultrasound classification, Hartofilakidis’ classification, Dunn’s classification, and so on. Due to the large population, the difficulty of census, the backward level of awareness and examination means, the insufficient funding for treatment, and the swaddling and wrapping habits in the northern region, DDH in China is characterized by late detection, late treatment, huge number of patients, and poor treatment effect. In terms of screening, diagnosis, treatment and prevention of DDH, China still has a long way to go.