The causes and pathogenesis of depression are not well understood and may involve biological, psychological, and environmental factors. From the perspective of biological factors, there are strong genetic, neurobiochemical and neuroendocrine relationships. Psychologically, depression is related to the patient’s personality traits, early upbringing, family relationships, early traumatic experiences, and stressful life events in adulthood, all of which are a cause of depression. In terms of social environment, intense environmental competition, increased stress, and living in a relatively closed environment for a long time, frustrated in interpersonal relationships, etc., can lead to depression. In addition, the onset of depression and certain physical diseases, as well as dependence on psychoactive substances, including certain drug factors can trigger depression and produce depressive manifestations. The treatment of depression is firstly the choice of antidepressant medication, and secondly would be the choice of psychotherapy, with medications mainly recommended like sertraline hydrochloride, paroxetine hydrochloride, fluoxetine, etc.