The asymmetry of the leg lines of three-month-old babies may be caused by physiological factors, which usually have little effect on the baby’s health. However, it may also be caused by pathological factors, such as hip dysplasia, which may affect the development, resulting in unequal length of the lower limbs. 1. Physiological factors, some physiological factors, such as uneven distribution of fat in the lower limbs, may cause the baby’s leg lines asymmetrical, generally does not have a greater impact on the baby’s body, do not need special treatment and therapy. 2. Pathological factors, some of the baby leg lines asymmetry may also be related to disease, such as hip dysplasia may appear leg lines asymmetrical symptoms. If the treatment is not timely, it may affect the baby’s later life, bone dysplasia, joint ligament laxity, joint inflammation, and may even lead to the double lower limbs are not equal. Three-month-old baby leg lines asymmetry, it is recommended to seek timely medical treatment to rule out disease factors, if necessary, timely treatment, to avoid affecting the baby’s physical development and health.