The invention belongs to medical equipment, and relates to an automatic constant-pressure skin dilator, which includes a silicon capsule and a water injection device connected by a water injection pipe. hole. The beneficial effect of the present invention is that it can detect the pressure, accurately grasp the internal pressure of the silicon capsule, facilitate the operation, and is convenient to use and store, and the hanging hole can be hung on the wall or shelf, and the sensor and the water pump can be used constantly. Manual operation is required, just hang it up to prevent it from being accidentally touched. After use, it can be hung on the utensil rack for easy storage. The thermometer can accurately measure the temperature of the liquid injected into the silicon capsule, and injecting a liquid with a suitable temperature is beneficial to reduce the pain of the patient.