In recent years, the high incidence rate and potential risk of sleep disordered breathing have been widely concerned. Obstructive sleep apnea syndrome (OSAS), as the most common sleep-related breathing disorders of all ages, has seriously threatened human health. Oral microecology is an important part of Human Microbiome Project. Its biological community structure and function are closely related to the occurrence and development of OSAS and its complications. This paper reviews the research on oral microecology and OSAS so as to provide reference for further clinical studies.