Dark red tongue coating may be caused by the depletion of fluid and the internalization of heat evil, which is the manifestation of Yin deficiency and fire exuberance (deficiency of Yin essence in the body and the appearance of hyperactive fire), and the common causes are overwork, excessive sexual intercourse, old age and prolonged illness, and so on. Yin deficiency and fire is caused by various reasons of heat, fluid depletion, will cause the tongue dark red or red tongue with little moss. Common causes include old age and chronic illness, depletion of qi and blood, too much intercourse, too much intercourse and depletion of kidney essence. Yin deficiency and fire is often accompanied by insomnia, tinnitus, blurred eyes, five heart heat (two palms and two feet heart heat, and consciously heart and chest heat), night sweating (abnormal sweating after going to sleep, waking up sweating to stop), the two ribs distension and pain, lumbar and knee soreness and weakness (lumbar and knee soreness and weakness of the sensation), men’s spermatorrhea, women’s menstrual period is low. Tongue dark red people daily to drink more warm water, eat a light diet, eat less spicy and fatty food; to pay attention to the combination of work and rest, keep in a good mood, live a regular life, do not often stay up late, sexual intercourse should be restrained. Tongue dark red if accompanied by other physical discomfort should be timely consultation, in the Chinese medicine practitioner under the guidance of the identification of treatment, do not self-medication.