The purpose of this study is to explore the characteristics and causes of Attention-Deficit Hyperactivity Disorder (ADHD), and the application of Cognitive Behavior Therapy (CBT) for Children with ADHD. The results were as follows: (a) Children with ADHD have many characteristics, including hyperactivity, behavioral disinhibition, inattention, learning disability about behavioral rules, and high variety of work performance and mood unstable. (b) Genes, Neurophysiology, pregnancy environment, and parenting style may cause ADHD of children. (c) This study finds the "Self-Regulation Strategy", "Self-Instructional Training" and "Self- Monitoring Method" of the CBT are useful for Children with ADHD.