目的：提高对小儿２１三体综合征脑部ＣＴ表现的认识和诊断。材料与方法：回顾性分析２３例经细胞遗传学检查证实的２１三体综合征的脑部ＣＴ表现。结果：本病的ＣＴ特征为：（１）脑内钙化，多见于基底节区，呈点状或小圆形；（２）侧裂、额顶区蛛网膜下腔增宽；（３）小脑发育不良。结论：本病ＣＴ表现具有一定的特征性，但其ＣＴ诊断须结合细胞遗传学检查确定。 Objective: To improve understanding and diagnosis of brain CT manifestations of trisomy 21 in children. Materials and Methods: The CT findings of 23 cases of trisomy 21 confirmed by cytogenetic examination were retrospectively analyzed. Results: The CT features of this disease were: (1) calcification in the brain, more common in the basal ganglia area, dotted or small round; (2) lateral fissure, frontal subarachnoid widened; (3) cerebellum Dysplasia. Conclusion: The CT features of this disease have certain characteristics, but the diagnosis of CT should be combined with cytogenetic examination to determine.