In recent years, with the improvement of the quality of living, people's pressure is increasing, accompanied by a variety of emotions, of which anxiety is themost common one. Anxiety disorder is also the highest incidence of all mental health problems, and there are co-morbidities with other anxiety disorders and depression. So, Will anxiety be the basis of these co-morbidity psychological problems? Based on this, the article reviews the clinical symptoms and pathogenesis of anxiety disorder, obsessive-compulsive disorder, phobia and depression, combs them according to their respective diagnostic criteria, and focuses on the relationship between anxiety and the above-mentioned mental disorders, in order to explore whether anxiety is the common cause of their occurence. It can provide a new perspective for a better understanding of anxiety and clinical diagnosis.