Objective To assess the reliability and validity of the Pittsburgh sleep quality index (PSQI) .Methods The cross-sectional survey was conducted in the outpatient department of this hospital .544 insomnia and non-insomnia voluntary participants (18-65 years old) from July to October 2011 were assessed with PSQI and the insomnia severity index (ISI) ,which were randomly delivered to them .Results The test-retest reliability of PSQI was 0 .994 .The split-half reliability coefficient of PSQI was 0 .824 . The overall Cronbach′s alpha coefficient was 0 .845 .The confirmatory factor analysis showed that the fitting indicators for the χ2/df ,root mean square error of approximation(RMSEA) ,non-normed fit index(NNFI) ,comparative fit index(CFI) and goodness-of-fit index(GFI) were 4 .83 ,0 .09 ,0 .96 ,0 .98 and 0 .97 respectively .The correlation coefficient between the PSQI and ISI was 0 .842 . The correlations coefficients between PSQI with the questionnaire type ,interview date and interview department were -0 .046 , 0 .276 and -0 .331 .Grouping by individuals with or without insomnia ,the area under the receiver operator characteristic curve (ROC) for PSQI was 0 .944(95% CI:0 .925-0 .963) .Conclusion PSQI has good reliability and validity ,and could be used for the sleep quality comprehensive evaluation in the patients with insomnia .