The purpose of the present study was to investigate the syntactic awareness skills of ADHD children using a word-order task. Twenty five children with ADHD and twenty five IQ, vocabuary skill and age-matched typically developing children participated in this study. All children were third to fifth grades in elementary schools. All participants were tested using a word-order task containing a variety of complex-sentence types in a total of 42 items(simple-sentence 12, complex-sentence 30). For simple-sentence, two-way ANOVA of subject group(2) x length(3) was conducted and for complex-sentence three-way ANOVA of subject group(2) x length(3) x type(5). The result showed for simple-sentence, significant main effect were found for group and length, but there was no group x length interaction effect. Complex-sentence result showed that significant main effect were found for group, length and type, and significantinteraction effect of group x length. These results suggested that children with ADHD appeared to poor syntactic awareness skills relative to there peers, and as sentence length increases, ADHD were more difficulty of syntactic awareness skills.