Objective: To assess the effects of Socioeconomic status on the dietary quality of children and adolescents, and to provide the reference for improving primary students’ dietary quality. Methods: A total of 2 496 students from 16 schools (4 urban primary schools, 4 rural primary schools, 4 urban middle schools, and 4 rural middle schools) in Fangshan District, Beijing, were included using a stratified cluster random sampling method. Information on 7-day intake of cereals, vegetables, fruits, meat and dairy was collected using questionnaires and dietary quality was graded according to the Dietary Guidelines for Chinese Residents (2016). Results: The dietary quality for urban children and adolescents was better than that for rural ones. Compared with rural children, their urban peers had higher scores for intake of vegetables, fruits, and dairy (all were P<0.01), but lower scores for intake of meat (P=0.01). For children with parental education level of senior high school, the dietary scores were higher in urban areas (P<0.05), whereas no urban-rural disparity was found for children with higher educated parents (junior college or above, P=0.17). In children with monthly household income less than 5 000 yuan, the urban dietary scores were higher than that of rural areas (P<0.01), whereas in the group above 5 000 yuan, the difference between urban and rural areas was no longer statistically significant(P>0.05). The multi-factor analysis showed that living in urban areas, being girls, being younger, with higher educated parents and with higher monthly household income were protective factors for dietary quality. However, the effect of household income on dietary quality differed between urban and rural areas (P<0.05). Conclusion In the process of dietary guidance and intervention, children with relatively low socio-economic level should be given a priority to provide appropriate nutrition education and welfare policies.