Hip dysplasia, also known as developmental hip dislocation, is mainly caused by structural deformities of the acetabulum, proximal femur and joint capsule, resulting in joint instability. The main performance of infants and young children in the pre-standing period is the unequal length of the lower limbs, to the child walking period standing period can cause limp, anterior pelvic tilt and other symptoms. 1. Pre-standing: i.e. infancy and childhood, the patient can not stand, the symptoms are often atypical. Hip dysplasia may cause asymmetric skin folds on both thighs, widening of the perineum, hip joints often in flexion, unable to straighten, hip joints with few and limited activities, and unequal length of both lower limbs. 2. Walking period: patients with hip dysplasia start walking later than normal children. One side of hip dysplasia will lead to limping. Bilateral hip dysplasia can lead to anterior pelvic tilt, anterior convexity of the lumbar spine, duck walking gait, and limited hip abduction. If you find hip dysplasia, you should go to the hospital in time and get early treatment under the doctor’s guidance, the earlier the treatment, the better the prognosis of the disease.