The difference between yin deficiency and yang deficiency is mainly manifested in the etiology, symptoms, treatments and prescriptions. 1. Etiology: Yin deficiency is generally due to fever or chronic illness, emotional exhaustion, unrestrained sexual intercourse, consuming too many warm and dry medicines and foods, old age, etc., resulting in a decrease in the body’s yin fluid, which can not nourish the body, and at the same time, yang qi is not constrained and overabundant, the symptoms of fever can occur. Yang deficiency is generally due to prolonged illness and exhaustion, long-term qi deficiency, living environment is too cold, consume too much cold food and medicines, old age, etc. leading to deficiency of yang qi in the body, can not warm the body, yin and cold is relatively overabundant. 2. Symptoms: Yin deficiency is characterized by thinness, dryness of the throat and mouth, warmth of the hands and feet, a burst of heat, and sweating while sleeping. Yang deficiency is characterized by fear of cold, cold limbs, lack of thirst and preference for hot drinks, excessive sweating, and scanty urine. 3. Treatment and prescription: Yin deficiency is treated by nourishing the yin fluid, and Chinese medicines or prescriptions such as Liu Wei Di Huang Wan and Maimendong Tang can be used for this purpose. Yang deficiency is treated by warming yang qi, and Chinese medicines or formulas such as Jin Gui Kidney Qi Pill and Pian Zi Lizhong Pill can be used for this purpose. If symptoms of yin or yang deficiency occur, please go to the hospital in time for diagnosis and treatment by a professional doctor.