The purpose of this study is to understand the etiology of child developmental disorder in terms of neurology. For that, the study reviewed neurological studies of reading disability, attention deficit-hyperactivity disorder, and autism spectrum disorder. At first, in the reading disability, it's main problem is phonological processing deficit. The important cortical areas that exhibit dysfunction of reading are the left superior temporal gyrus(STG) and the left fusiform. STG is involved in phonological processing, and the fusiform is associated with the automatic process of visual word form perception. Next, ADHD combind type(ADHD/C) is different from ADHD inattention type(ADHD/I) in behaviour characteristics and neurological dysfunction. A number of studies have suggested an inhibitory deficit that is associated with right prefrontal lobe in ADHD/C. In contrast, ADHD/I exhibit sluggish cognitive tempo symptoms. But, the neurological study for ADHD/I is lack. Then, it had reported that language/communication problem of autism spectrum disorder is associated with dysfunction of left temporal lobe, STG, and Broca's region. In problems of social interaction of autism spectrum disorder, it is shown that the dysfunction of the medial prefrontal lobe, the orbital prefrontal lobe, the fusiform, and the amygdala is associated with them. Finally, the significance and directions of the study was proposed.