Subhealth is a state in which the human body is in between health and disease, and people in a subhealthy state cannot meet the standard of health. It is called subhealth because it is characterized by symptoms of reduced vitality and reduced functional and adaptive capacity within a certain period of time, but it does not meet the clinical or subclinical diagnostic criteria of modern medicine regarding diseases. The main features of subhealth include various symptoms reflected by the feeling of physical and mental maladjustment, such as fatigue, weakness, emotional changes, etc., the condition of which is difficult to be defined for a considerable period of time, various manifestations of weakness due to age incompatible tissue structure or physiological function decrements, as well as the state of micro-ecological imbalance and the pre-pathological and pathological changes of certain diseases, all of which belong to subhealth.