Limited evidence exists regarding the effect of exposure to ambient particle matters with aerodynamic diameter < 1 μm (PM₁) in a short-term on blood pressure (BP) in the pediatric population. This study aims to examine the association between short-term exposure to ambient PM₁ on BP in children and adolescents. Population data were obtained from a large cross-sectional survey from 102 schools in Shandong Province, China. Daily air pollution data were collected, and individual exposure level was assigned based on coordinates of school addresses. Distributed lag non-linear models incorporated with a linear mixed model were used. A total of 35241 students aged 9-18 years were included in the study, and the mean values of PM₁, particle matters with aerodynamic diameter <= 2.5 μm (PM_2.5), and < 10 μm (PM₁₀) at the schools during the study period were 50.8 (SD = 7.2) μg/m³, 75.5 (SD = 14.7) μg/m³, and 138.9 (SD = 25.9) μg/m³, respectively. We found that per 10 μg/m³ increment in a cumulative exposure of PM₁ at lag 0 and lag 1 day was significantly associated with a higher systolic BP (SBP, β = 1.46 mmHg), diastolic BP (DBP, β = 1.20 mmHg, 95% CI = 0.52 to 1.88), mean arterial pressure (MAP, β =1.28 mmHg, 95% CI = 0.61 to 1.96), and pulse pressure (PP, β = 0.65 mmHg, 95% CI = 0.14 to 1.16), after adjusting for other air pollutants and individual covariates (including sex, age, BMI, residence, month of the survey, intake of eggs, intake of milk, physical activity, and screen time). The above associations were stronger in magnitude than for PM_2.5- and PM₁₀- related associations. The associations of PM₁ with SBP, DBP, MAP, and PP were stronger among females, younger children, those overweight or obese, and those with insufficient physical activity levels. In conclusion, the susceptible window of short-term exposure to ambient PM₁, PM_2.5 and PM₁₀ on BP levels for children and adolescents are lag 0 and lag 1 day, with PM₁ exhibiting a stronger association. Future interventions should be conducted to reduce the impact of PM exposure, especially PM₁, on health in children and adolescents.