The baby sleeps with his legs curled up, that is, the child’s double lower limbs tibia bent to the outside of the sleeping position, is mostly normal and a physiological phenomenon. Because the fetus’ limbs are mostly flexed when in the mother’s womb, the child will also maintain this position after birth, including when sleeping. As long as the child sleeps peacefully, comfortably, naturally, and with a sense of security, parents do not need to worry too much, as the months grow older, the child’s limbs will naturally stretch, this phenomenon will slowly disappear. Some parents stretch the child’s legs straight, tied up with cloth, this practice is wrong, parents should not forcibly give correction, so as not to affect the normal growth and development of the baby. However, attention should also be paid to exclude abnormal manifestations of neurological damage due to postnatal asphyxia and hypoxia, abnormal brain development and other conditions, such as the performance of flexed legs with high muscle tone in both lower extremities, must be hospitalized for early detection and early intervention and treatment.