The skin is located on the surface of the human body, from the skin can reflect the health of the whole body. A healthy, well-nourished person has a rosy complexion and lustrous, elastic skin. When the health status is not good, the face is often gaunt and the skin is dull. Changes in the skin can be a precursor or indicator of a systemic disease. For example, a woman with chronic low fever and joint pain, when butterfly-shaped erythema appears on the face, it indicates a likely case of lupus erythematosus. If an elderly person has itchy skin and is prone to folliculitis, boils, or Candida infection, a blood glucose and urine sugar test should be performed to rule out diabetes. When soft orange-yellow patches appear in the inner canthus of the upper eyelid, blood lipid tests should be performed to alert for hyperlipidemia, and diet should be controlled, mainly by restricting a high-fat diet. Recurrent paroxysmal skin flushing with intestinal rales, diarrhea, and asthma-like attacks should be noted to rule out a neuroendocrine tumor, carcinoid syndrome. The skin can be the first symptom of a serious systemic disease, so when diagnosing and treating skin diseases, we must have a holistic view and consider the skin as an important part of the organism. It is important to consider the skin as an important part of the organism. We should not “see the trees but not the forest” and “treat the headache and the foot” to avoid delaying the treatment.