Bilingual mean that we should be able to speak in two languages. The discussion of bilingual is the very important matter today, lots of studies and viewpoints have done on this issue; because there are many kids in the same time, they speak in two languages, they learn one language as their mother language and the second language they could learn from their other family members or sometimes even they learn third language in the area where they live and grow up. Children can learn the language since their born till they enter to the society or in the educational areas like; preschool, schools and so on. They can also learn language naturally or learn it official. In different countries lots of studies have done on bilingual and results of those investigations show that the children who are bilingual have high intelligence, and speaking in two languages causes children grants a lot of potential thinking, the child grows smarter and more talented; but despite in Afghanistan more children are bilingual, less research has done on this issue. The aim of this review was to evaluate the role of bilingualism on learning of bilingual children. The results of this study indicated that children who are bilingual have high intelligence and speaking in two languages makes children keener their potential thinking, and this kind of children are more talented and able than the other children who are monolingual. As much children start speaking in two languages since their born, their brains' actions grow more.