It can be summarized as follows: 1. Based on WHO’s new concept of four-in-one health, subhealth can be divided into: (1) physical subhealth. The main manifestations are physical fatigue, weakness, peripheral discomfort, decreased sexual function and menstrual cycle disorders of unknown or excluded causes; (2) mental sub-health. Mainly manifested as unexplained brain fatigue, emotional disorders, disordered thinking, panic, anxiety, low self-esteem, as well as neuroticism, apathy, loneliness, rashness, and even suicidal thoughts, etc.; (3) social adaptation subhealth. Focused on the difficulty in adapting to the work, life, study and other environments, and the difficulty in coordinating interpersonal relationships; (4) moral. The main manifestation is the existence of obvious deviations in the world view, outlook on life and values that are harmful to others and to oneself. 2, according to the classification of the components of the concept of sub-health: (1) physical and mental discomfort, but difficult to diagnose the “indefinite statement syndrome”; (2) the pre-clinical manifestations of certain diseases (pre-disease state); (3) a momentary difficulty in clarifying the pathological significance of the “unexplained syndrome (3) “unexplained syndrome”, such as menopause syndrome, neurasthenia syndrome, fatigue syndrome, etc.; (4) certain pathogenic carrier status: such as hepatitis B carriers, tuberculosis carriers, carriers of certain viruses, etc.; (5) certain clinical examination of high and low limit value status, such as high blood lipids, blood pressure, heart rate, etc. and low blood calcium, potassium, iron, etc.; (6) high pathogenic (6) High pathogenic risk factors, such as overweight, smoking, excessive stress, abnormal blood lipids, blood sugar, blood pressure, etc. 3. According to the body structure and system organs, they are divided into subhealth states such as neuropsychiatric system, cardiovascular system, digestive system, bone and joint system, genitourinary system, respiratory system, and special senses. Scientific understanding of sub-health, distinguish sub-health and related medical problems: 1, it is not equal to chronic fatigue syndrome (CFS). First of all, CFS has international standard, but subhealth has not; secondly, the incidence of CFS in adults over 18 years old is only 0.004%, while subhealth is 70%, which is a big difference between the two; furthermore, most of the subhealth states described in China can be restored to health through active intervention, while only 30% of CFS can be restored to a healthy state. 2. Subhealth is different from subclinical: Although subhealth is partly overlapping with the upstream health state and the downstream disease state, the distinction is also obvious. For example, in the current common subclinical carotid atherosclerosis in middle-aged and elderly people, carotid ultrasound examination reveals more obvious carotid intima-media thickening and even plaque formation without clinical manifestations; while people in subhealthy state have complaints of headache, dizziness and chest discomfort, but vascular heart ultrasound and electrocardiogram examination do not reveal any abnormalities. 3, the definition of sub-health should also pay attention to the distinction with the early diagnosis of clinical functional diseases and psychosomatic disorders and certain diseases. At present, there is no unified standard for suboptimal health, and there are great differences in the understanding and definition of suboptimal health between Chinese and Western medicine, which are problems to be solved in the future.