Objective To explore the application of portable sleep monitor (PM) to the diagnosis obstructive sleep apnea hypopnea syndrome (OSAHS) in adults. Methods A PM system was applied to 34 adult patients with suspected OSAHS, and polysomnography (PSG) as the gold standard to evaluate the diagnostic efficiency of PM system. Results The differences of apneahypopnea index (AHI), oxygen desaturation index (ODI), the lowest SpO2 (LSpO2) and the mean SpO2 (MSpO2) between the two kinds of monitoring systems were statistically insignificant (P>0.05). Regarding PSG as golden standard, the sensitivity, specificity and the accuracy of PM was 100%, 75%, and 97.14% respectively. Conclusion As a simple, convenient, sensitive detection method with high diagnostic value for OSAHS in adults, PM is worthy of clinical application. 