Patients can take a sitting or supine position, try to open the mouth, so that the tongue body is fully exposed, the tongue will naturally stick out of the mouth, the tip of the tongue slightly down, and then observe the tongue image, generally look at the tongue quality first, and then look at the tongue coating, the order is from the tip of the tongue, tongue, tongue side to the root of the tongue. It is not easy to look at the tongue for too long, because too long may cause dryness. In addition, you can also identify the tongue with or without roots and whether it is a dyed moss by the method of carding the tongue. When looking at the tongue, one should also pay attention to the influence of light, as well as the influence of diet and medicine, and the influence of oral conditions on the tongue, as well as knowing the normal tongue image and its physiological variation. To see the quality of the tongue, one should look at the tongue’s appearance and color, and the other should look at the shape and quality of the tongue.