Objectives To study the value of cough peak expiratory lfow (CPEF) in predicting extubation outcome of children with acute respiratory failure. Methods A total of 62 children with acute respiratory failure were selected and received mechanical ventilation longer than 72 hours. They were conscious at the time of extubation and successfully got through 30 minutes of spontaneous breathing trial. Children were divided into success group and failure group according to the outcome of extubation. CPEF, pulmonary function parameters, blood gas analysis and pediatric critical illness scores were compared before extubation between two groups. Results Fifty-two cases were successfully extubated but 10 cases failed. CPEF of the success group was signiifcantly higher than that of the failure group (P<0.01). Based on the results of receiver operating characteristic curves, the area under the curve was 0.873. The optimal operating point of CPEF was 40.5L/min, and the sensitivity and speciifcity were 76.9%and 90.0%, respectively (P<0.01). Conclusions It is suggested that CPEF can be used as a predictor of extubation outcome.