1. Due to the special anatomical structure of cleft lip and palate, the lip is cleft, the oral and nasal cavities are connected, and the mouth cannot form a complete airtight structure to produce the negative pressure required for effective sucking. 2. Due to the cleft palate, the distribution of the muscles and the change of attachment cause the development and tension of the muscles to change. This causes the tongue to retract; at the same time, the tongue is overdeveloped and the tongue is not raised to effectively wrap the pacifier during sucking. 3. The shortening or inability to lift the soft palate causes imperfect function of the soft palate and affects sucking and swallowing.