Objective To analyze the emergency-event in patients with obstructive sleep apnea-hypopnea syndrome( OSAHS), and to discuss the risk factors and preliminary strategies for prevention of emergency-event. Method A total of 257 OSAHS patients in Zhejiang Provincial Peoples Hospital, were enrolled from January 2000 to December 2009 for the retrospective study. Demographics of patients include age, sex,height, weight, related diseases, AHI and LSaO2 before operation , the way of anesthesia and operation,when and how the emergency-events happened, the way to cure and the results. Risk facts of emergency-event were analyzed by using univariate analysis and multiple logistic regression analysis. Results Of the 257patients, the incidents of emergency-event was 7.3%. The independent risk factors of emergency-event were general anesthesia, multiple level surgery in one time, BMI and AHI. Performing CPAP treatment before operation had a beneficial effect to the avoidance of emergency-event. Conclusions Emergency-event are more common in severe OSAHS patients, especially when they were operated under general anesthesia and multiple level surgery in one time. Performing CPAP treatment before operation had a beneficial effect to the avoidance of emergency-event.