Objective:To test the validity and reliability of the University of California at Los Angeles Posttraumatic Stress Disorder Reaction Index for DSM-Ⅳ (Revision 1,Children version) (UCLA PTSD-RI) in Chinese Children after flood.Methods:On the principle of convenient sampling,the students were chosen from 6 schools in Liaoning Province where was hit by flood.Totally 1593 students [aged 8-16 years,average (11 ± 2) years of age]completed the UCLA PTSD-RI.They were randomly divided into two groups for exploratory factor analysis (n =796) and confirmatory factor analysis (n =797) respectively.The 21-item Depression Anxiety Stress Scale(DASS-21) were used to evaluate the criterion validity.Results:The result of exploratory factor analysis indicated UCLA PTSD-RI consisted of 3 factors,accounting for 50％ of the total variance.The confirmatory factor analysis identified that a three-factor model fit well (x2/df=3.87,GFI =0.93,RFI =0.96,CFI =097,NNFI =0.97,IFI =0.97,RM-SEA =0.06).The scores of UCLA PTSD-RI subscales were positively correlated with the scores of DASS-21 subscales (r =0.52-0.70,Ps ＜ 0.001).The Cronbach's a coefficient and the split-half reliability coefficient of UCLA PTSD-RI were 0.90 and 0.87,respectively.Conclusion:The Chinese Version of the UCLA PTSD Reaction Index for DSM-Ⅳ (Revision 1,Children version) could be an effective instrument for assessing and diagnosing PTSD of Chinese children after disasters.