Abstract: With the improvement of living standards， fat people tend to be more and more. Obesity is becoming increasingly important in causing a series of related diseases such as hyperlipidemia， diabetes， respiratory diseases and so on. But  obesity hypoventilation syndrome (OHS) which is easy to be ignored but has clinical significance  can seriously affect the patient respiratory， cardiovascular and endocrine system. If OHS not timely corrected，  the prognosis is poor， including respiratory failure， arrhythmia， heart failure and so on. This paper provides a review on OHS conception，pathogenesis， clinical manifestations and diagnostic criteria and treatment. OHS deserves more attention.

Key words: obesity hypoventilation syndrome, hypercapnia , noninvasive ventilation;leptin