Ｏｂｊｅｃｔｉｖｅ　To observe the skin temperature changes induced by ultrasound-guided axillary brachial plexus block in pediatrics under general anesthesia and explore the accuracy of the temperature changes in predicting the effect of nerve block.　Methods　Thirty pediatric patients undergoing upper extremity surgery were selected for this study. After anesthesia induction, a laryngeal mask airway was inserted, and then the ultrasound-guided axillary brachial plexus block was performed. After the block sites were determined, one quarter of the total dose(1 ml/kg) of 0.25% ropivacaine was injected around the four main branches of axillary brachial plexus, respectively. The testing sites of each block area were randomly selected. The skin temperature at the time of 15 min before nerve block and 15 min after were recorded, and the skin temperature changes were calculated. The sensitivity and specificity of the temperature changes in determining the success of axillary brachial plexus block was assessed by using the receiver operating characteristic(ROC) curve. Spearman correlation was used to analyze the correlation between them.　Results　The value of area under curve(AUC) of the ROC of the skin temperature changes in blocked area were 0.886[95% confidence interval(CI): 0.815-0.957]. The addition of the sensitivity and specificity arrived the maximum at the diagnostic cut-off value of 0.65 ℃, which was 86.4% and 94.1%, respectively. The value of Spearman′s correlation coefficient was 0.773(95%CI: 0.656-0.840).　Conclusions　The present study demonstrated that the changes of the skin temperature in blocked area have a high accuracy in predicting the effect of nerve block, which can be used in determining the success of axillary brachial plexus block under general anesthesia in pediatrics.