Depression and chronic fatigue syndrome are heterogeneous disorders that share similarities in symptoms and common candidate biomarkers，with unique differential metabolites.They have potential associations in pathogenesis mechanism.This paper focused on the similar characteristics of depression and chronic fatigue syndrome，and took “strange disease is related to phlegm” as the entry point.It was believed that phlegm-qi mutual obstruction was the common pathogenesis of these two diseases，and dysfunction of zang-fu organs-disorder of qi movement-turbid phlegm formation-blockage of qi movement-damage of zang-fu organs is the common disease pathway.In the research and clinical work of depression and chronic fatigue syndrome，we should emphasize the mutual relationship between “phlegm” and “qi”，to give full play of the advantages of traditional Chinese medicine in treating different diseases with the same method in the prevention and treatment of difficult chronic diseases and enrich the theoretical connotation.