Objective: This study is conducted to establish the norms of the width and length of the dental arch on normal occlusion in Chongqing teenagers and to analyze the characteristics in arch dimensions

in order to provide the reference for diagnosis in orthodontics.Methods: 92 cases of normal occlusion dental model in Chongqing teenagers(45 boys and 47 girls) were selected.The width and length of the dental arch were measured with a vernier.The measurements were analysed with statistic methods and compared with those of different groups.Results: The width and length of the dental arch in boys were larger than those in girls.The form of dental arch of both boys and girls was oval.Conclusion: There were distinguishing characteristics in arch dimensions on normal occlusion in Chongqing teenagers.Ethnic differences should be considered in orthodontics.