Abnormal sucking function is one of the major causes of malocclusion formation. Sucking is an important oral function that infants have at birth. It not only helps infants to obtain the necessary nutrients for their bodies, but also promotes their oral growth and development. At birth, the infant’s lower jaw is in a far-neutral position. Through normal breastfeeding, a certain amount of functional stimulation is given to the lower jaw to promote its growth while guiding it to adjust to a neutral position. Artificial feeding, on the other hand, due to bottle position or incorrect feeding posture, etc., makes their jaws under-extended or over-extended forward, resulting in distal-medial jaw misalignment or mandibular protrusion deformity. Therefore, we should allow infants to have adequate and correct sucking so as to reduce the occurrence of malocclusion.