Secretory otitis media (SOM) is a non-suppurative otitis media characterized by conductive hearing loss and tympanic effusion without acute inflammatory manifestations. Its etiology and physiological mechanisms are complex, mainly ear symptoms such as ear tightness, tinnitus, and earache, etc. It can occur at all ages, especially in preschool children. At present, the etiology and pathogenesis of SOM have not been fully elucidated. Composition analysis of SOM middle ear effusion is a common method to study the etiology and pathogenesis of SOM, as well as an important way to guide clinical treatment. This paper compares and summarizes the research progress of SOM middle ear effusion by referring to relevant literature published at home and abroad, so as to improve understanding of clinicians in this disease.