According to statistics, about 15% to 30% of adults have experienced depressive symptoms at some point in their lives, but they are not necessarily pathological. Because ordinary people also feel depressed and sad when they encounter something unpleasant, generally speaking, only when the degree is severe and prolonged and social functioning is affected is it considered pathological. Therefore, having depressive symptoms does not necessarily lead to a diagnosis of depression. Symptom criteria, temporal criteria, severity criteria, and exclusion criteria must be present to diagnose depression. Generally speaking, depressed mood is the main symptom and at least the following symptoms: 1. no pleasant feeling; 2. reduced energy or fatigue; 3. psychomotor retardation or agitation; 4. low self-esteem, self-blame, or guilt; 5. difficulty in association or reduced ability to think for oneself; 6. recurrent thoughts of death or suicidal or self-injurious behavior; 7. sleep disorders, such as insomnia, early awakening, or excessive sleep; 8. Decreased appetite or significant weight loss; 9. Decreased sexual desire. Depressive symptoms lasting at least 2 weeks, and the resulting impairment of the patient’s social functioning, or distress or adverse consequences for the patient, also exclude other diseases. For example, organic brain mental disorders, mental disorders due to physical illness, mental disorders due to psychoactive and non-dependent substances. Depression can be diagnosed as long as the above criteria are met. Another condition that can be easily misdiagnosed is patients with somatic pain symptoms, most of whom first visit general hospitals and are correctly diagnosed with depression only after several visits. Among depressed patients, there is a high prevalence of painful somatic symptoms, most commonly headache, back pain, gastrointestinal pain, and unspecified pain. A study by the World Federation for Mental Health showed that 69% of patients diagnosed with depression presented with unexplained somatic symptoms as their chief complaint at the time of medical consultation; 43% of diagnosed patients suffered from chronic painful somatic symptoms. Therefore, people should learn to recognize depression and get timely psychological help and standardized treatment.