Depression is mainly characterized by low mood, during which at least four of the following symptoms are present and persist for more than two weeks, it is recommended to seek medical treatment. 1. The degree of depressed state of mind varies and can range from a mildly poor state of mind to sadness, pessimism and despair. Patients feel heavy, life is not meaningful, happy, depressed, spending time like years, painful, can not be self-reliance. Some patients may also appear anxious, easily agitated, nervous and restless. 2.Loss of interest is one of the common symptoms of depressed patients. Loss of enthusiasm and pleasure in life and work, and loss of interest in everything. The patient does not experience the joy of family, does not care about the past hobbies, often lives alone behind closed doors, alienates friends and relatives, and avoids social life. Patients often complain of “no more feelings”, “emotional numbness”, “no more happiness”. 3. Loss of energy, fatigue and weakness, difficulty in washing, dressing and other small daily tasks, and inability to cope with them. Patients often use the words “mental breakdown” and “deflated ball” to describe their condition. 4. Low self-evaluation: Patients tend to excessively devalue their own abilities, and view their present, past and future in a critical, negative and negative manner, describing themselves as useless and having a dark future. Strong feelings of self-blame, guilt, uselessness, worthlessness, helplessness, and in severe cases, self-criminality and suspicion may appear. 5.Patients show significant, persistent and general depression, difficulty in concentration, memory loss, slow brain, closed mind, slow action, but some patients show restlessness, anxiety, tension and agitation. 6, negative pessimism: very painful, pessimistic, despair, feel that life is a burden, not worth staying, to die for relief, may produce strong suicidal thoughts and behavior. 7, somatic or biological symptoms: depressed patients often have biological symptoms such as loss of appetite, weight loss, sleep disorders, low sexual function and diurnal fluctuations in mood, very common, but not in every case:? Loss of appetite and weight loss: Most patients have poor appetite, poor appetite symptoms, delicious food is no longer tempting, patients do not think about tea and food or tasteless, often accompanied by weight loss. Sexual dysfunction: Early in the course of the disease, the libido may be reduced, men may become impotent, and female patients may experience a loss of sensuality. Sleep disorders: The typical sleep disorder is early awakening, 2 to 3 hours earlier than usual, not falling back to sleep after waking up, and falling into a sad atmosphere. Diurnal variation: The patient’s state of mind has a diurnal variation of heavy day and light night. In the early morning or morning, the patient falls into a low mood, and in the afternoon or evening, the patient gradually improves and is able to have a short conversation and a meal. The incidence of diurnal variation is about 50%.