Objective To analyze the awareness of nutritional health knowledge among school-age children in Sichuan Province, identify shortcomings and related issues of nutritional health knowledge, and provide a scientific basis for nutritional intervention policies. Methods From October 2023 to May 2024, a multi-stage sampling method was used to collect nutritional health knowledge questionnaires from 12 674 school-age children in 21 districts and counties of Sichuan Province through a questionnaire survey. Descriptive statistical analysis and multivariable analysis were conducted based on survey content. Results The nutritional health knowledge scores [median (interquartile range)] of school-age children in Sichuan Province (including lower elementary school students) in 2023—2024 were 73.00 (63.00-84.00). Scores for lower elementary, upper elementary, middle school, and high school groups were 90.00 (80.00-95.00), 72.00 (62.00-82.00), 69.00 (58.00-77.00), and 66.00 (57.00-74.00), respectively. The higher the grade level, the lower the score, and this was statistically significant. The score rate ranges for the five knowledge dimensions of dietary recommendations, food classification and characteristics, food and growth development and health, food selection, and food safety were 54.82%-81.66%, 60.31%-91.40%, 69.85%-89.50%,71.65%-86.20%, and 69.38%-84.07%, respectively. The lower elementary school grade group had the highest score in each knowledge dimension, and the senior high school group had the lowest score rate. The awareness rate (excluding lower elementary grades) was 32.98%, and the awareness rates for upper elementary school grades, middle school, and high school were 41.91%, 31.12%, and 23.34%, respectively. The higher the grade level, the lower the awareness rate, and this was statistically significant (χ²=249.432, P<0.001). Univariate analysis results showed that gender, grade level, region, whether living on campus, the educational level and occupation of the parents of school-age children had statistically significant differences in the awareness rate of nutritional health knowledge (P<0.05). Logistic regression analysis results showed that the grade level, region (urban or rural), whether living on campus, father’s education and occupation were important factors affecting the awareness level of nutritional health knowledge among school-age children in Sichuan Province. Conclusion There is significant room for improvement in the awareness rate of nutritional health knowledge among school-age children in Sichuan Province. To improve the nutritional health literacy of school-age children, it is necessary to further strengthen the publicity and education of nutritional health knowledge.