Objective To observe the influencing factors of polysomnography (PSG) monitoring and to evaluate the efficacy of preventive measures.Methods We selected 205 patients with sleep apnea syndrome (SAS) who accepted PSG from May 2011 to April 2012 in our hospital as the intervention group.They were administered preventive measures,including psychological counseling,intensive grease dispelling of patient skin,arrangement of sensor and electrode.One hundred and fifty-two SAS patients who were administered PSG from May 2010 to April 2011 were selected as the control group.The monitoring successful rates between groups were compared and influencing factors were investigated.Results The monitoring successful rates of control group and the intervention group were 92.1％ and 97.1％ respectively; there was a statistically significant difference between the successful rates of the two groups (x2 =4.499,P ＜ 0.05).The main causes for unsuccessful monitoring were difficulty falling asleep,electrode distortion and high impedance of electrode.Conclusion PSG monitoring has a complex operating procedure and is time-consuming and effective preventive measures can improve the successful rate of PSG.