Mouth old off a layer of white film like skin may be salivary protein film, bad habits, mouth ulcers, Candida albicans infection, herpetic aspergillosis and other causes. 1. Salivary protein film: because saliva is protein and water, after a night of deposition, stained with water to form a film. The skin in the mouth and the white membrane is actually a mixture of salivary protein film and food residue, not really lose skin. 2. Bad habits: If the patient develops the bad habit of frequently rubbing or biting with the teeth in the upper and lower buccal mucosa, it will lead to epithelial surface layer detachment. It may also be the normal physiological shedding of oral epithelial cell metabolism. 3. Mouth ulcers: often eat spicy and irritating food or by bacteria, viruses, other pathogens invasion may lead to mucosal tissue lesions, mouth ulcers, resulting in the mouth of a layer of old white film like skin. 4. Candida albicans infection: when the body’s immune system is low, it may lead to Candida albicans infection, especially thrush, which will lead to white pseudomembrane presence in the mouth. 5. Herpetic pemphigoid: Herpetic pemphigoid is an autoimmune disease that causes the oral mucosa to fall off easily and tear off easily. If the patient appears in the mouth old off a layer of white film like skin, should promptly seek medical attention, under the guidance of the doctor, to take the appropriate treatment program.