Objective To establish the self-concept growth curve of school-age children and adolescents in China, discover developmental rules, and find and intervene developmental deviations early. Methods Relying on the accelerated longitudinal cohort data for healthy children and adolescents from“Chinese Color Nest Project：growing up in China”（devCCNP）, 399 typically developing children and adolescents（62 completed two longitudinal waves）completed the Piers-Harris children’s self-concept scale（PHCSS）to assess developmental levels of self-concept, and then a generalizedadditive mixed model（GAMM）was proposed to construct their growth curves. Results The modeling of growth curves indicated that the global self-concept scores decreased linearly with age in girls, and increased at first and then decreased in boys, showing an inverted U-shaped curve. Meanwhile, the main effects of physical appearance and attributes（P=0 .044）and freedom from anxiety（P< 0 .001）were significant between the two groups. Conclusion School-age children and adolescents develop their self-concept differently in gender. The growth curves showed a continuous reduction of the self-concept in girls and a turning point at the age of 10 in boys. Both girls and boys experience dramatic changes of freedom from anxiety, and more attention should be paid by school and family education practice.