The middle sulcus is one of facial features, located in the center of nasolabial sulcus, extending from the tip of nose to the upper lip. The depth of human sulcus is not only an appearance feature, but also reflects the health status of human body. The depth of human gingival sulcus is closely related to health, which reveals that the health code of human gingival sulcus depth is very important for our life and health.