Yin deficiency and yang deficiency are the basic methods to distinguish between physical constitution in Chinese medicine. Yin deficiency and yang deficiency are the most basic classifications, and there are several points to master to determine whether the body is Yin or Yang deficient. First of all, we need to clarify the relationship between yin and yang: yin and yang are relative, yang represents the sun, the meaning of warmth, and yin is the moon, the meaning of cold. The meaning of deficiency: the name means lack, lack, lack of meaning. Yang deficiency is the lack of Yang, Yin deficiency is the lack of Yin. Yang deficiency is mainly characterized by pale face, cold limbs, fear of cold, preference for warmth, pale white tongue, sunken and sluggish pulse, easy drowsiness, heavy body, dislike of exercise, women prone to uterine cold, irregular menstruation, dysmenorrhea, dark color, men prone to impotence, premature diarrhea, weakness of the waist and knees, etc. Yin deficiency is characterized by flushing of the face, irritable heat in the heart, night sweating, emaciation, light red tongue, fine pulse, frequent irritability, insomnia and dreaminess, irregular menstruation with deficiency heat in women, spermatorrhea, weakness of the waist and knees in men. Yin deficiency and Yang deficiency also have some common manifestations, such as weakness of the waist and knees and weakness of the body, and sometimes the symptoms of Yin deficiency and Yang deficiency often exist at the same time, both Yin and Yang deficiency. The above are the manifestations of Yin deficiency and Yang deficiency, the treatment differs from case to case, the specific situation should be treated after the clinician identifies the evidence to avoid delaying the condition.