Dry mouth with a layer of white may be the secretion of oral salivary glands, lip debris and saliva mixture. At night, the secretions of the salivary glands of the mouth may not be swallowed or discharged in time, and when the water evaporates, the viscous protein substances therein adhere to the lips, thus appearing to form a layer of white material. When the body lacks vitamins, the symptoms of flaking on the surface of the lips will appear, and when mixed with saliva, a white film will form when the water on the surface of the lips evaporates, and thus a white layer of dry mouth may appear. When there is a white layer of dry mouth, it is recommended to drink more water, apply lip balm, if long-term non-relief, and accompanied by other discomforts, it is recommended to consult a doctor in time to clarify the cause.