A one-year-old baby walking a little loopy, may be normal, but also to consider vitamin D deficiency, knee joint development abnormalities. 1. Physiological phenomenon: the baby’s fetal period by the intrauterine influence, the lower limbs are in a state of curling, after birth, the lower limbs will be slightly internally rotated, with the weight of the ground to walk, the symptoms gradually improve. In addition, by genetic factors, may also appear lower limbs slightly curved. 2. Vitamin D deficiency: not timely supplementation of vitamin D after birth or short exposure to sunlight, resulting in vitamin D deficiency, affecting the body’s calcium and phosphorus metabolism and absorption, softening of the bones, manifested in the phenomenon of O-shaped legs, which is not normal. 3. Knee development abnormalities: If congenital knee development abnormalities, or trauma after birth, may affect the knee joint, manifested as lower limb bending. A one-year-old baby walking a little loopy may also be related to other reasons, it is recommended to take the child to the hospital to exclude the factors of disease.