Today, attention to socially vulnerable groups, especially children, in the process of designing and planning the city's most important issues and Maximum attention is focused on experts and administrators manage the city. On the other hand, modification of the urban environment for children through urban design solutions, demonstrates a sense of responsibility towards the children of the professional architectural and urban planning. And will be training and responsibility in children and adolescents. Suitable for children and adolescents because the environment did not encompass costs and only requires knowledge, respect and responsibility among authorities and professionals. Accordingly, in this paper, fundamental and problem-based approach, and using the method of “analytical” and “logical reasoning” and policy research to study the aspects of child-friendly cities studied. And urban design guideline is considered child-friendly cities. Finally, in brief, the principles and design criteria are referred to child-friendly cities.