Objective  To analyze the health condition of children with attention-deficit/hyperactivity disorder (ADHD). Methods  The study was based on the National Multicenter Sleep Research Database, which was collected from 9 cities with 23 791 school-age children in grades 1-6. Height and weight were measured by school doctors according to the standard method. Children with ADHD diagnosed by specialists were ADHD group and the others were non-ADHD group. According to the standards of children aged 2-18 years in 9 cities of China in 2005, they were diagnosed as underweight, growth retardation, marasmus, and overweight/obesity. Using preterm infants, sleep quality and previous diseases as independent variables, and diagnosed ADHD as dependent variables, a binary Logistic regression model was established. Results  The records of 18 731 school-age children were analyzed, within 808 ADHD children. Compared with the 5.9% growth retardation rate of non-ADHD children, the growth retardation rate of ADHD children was as high as 9.8% (χ²=20.353, P<0.001), which was  mainly concentrated in the age group of 6-9 years. The rate of overweight/obesity in ADHD children was 32.6%, which was higher than 29.6% in non-ADHD children (χ²=9.904, P=0.002). The rate of marasmus in ADHD boys was 7.5%, which was higher than 5.3% in non-ADHD boys (χ²=4.877, P=0.027). Premature infants (OR=1.838, 95% CI: 1.393-2.423), allergic diseases (OR=1.915, 95% CI: 1.526-2.399), otitis media (OR=1.549, 95% CI: 1.118-2.146), tonsil or adenoid hypertrophy (OR=1.662, 95% CI: 1.348-2.050, gastroesophageal reflux (OR=3.008, 95% CI: 1.792-5.049), and sleep dysfunction (OR=2.201, 95% CI: 1.847-2.623) were risk factors for ADHD in school-age children. Conclusion  The nutrition of school-age ADHD children is in a two-level state, especially for boys. It is suggested that clinical nutrition management should be carried out simultaneously with drug and behavioral therapy.