Objective: To investigate the dose response relationship between waist-to-height ratio (WHtR) and elevated blood pressure among primary and secondary school students in Meishan City, so as to provide a reference for precise prevention and control of elevated blood pressure in children and adolescents. Methods: From September to October 2025, a stratified cluster random sampling method was used to select 10 399 primary and secondary school students in Meishan City for measurements of height, weight, waist circumference, and blood pressure. Chi-square trend test, Logistic regression and restricted cubic spline model were used to analyze the association and dose response relationship between WHtR and elevated blood pressure among primary and secondary school students. Results: WHtR showed a linear association with elevated blood pressure among boys of all age groups (7-11，12-14，15-17 years) groups and girls aged 10-12, 13-15, and 16-17 years (all P non linear >0.05); whereas girls aged 7-9 years exhibited a U shaped association ( P non linear<0.05). WHtR was stratified by age and sex and divided into quartile groups ( Q1-Q 4). Multivariate Logistic regression analysis showed that after adjusting for age and body mass index (BMI), the risks of elevated blood pressure increased among boys in groups Q2-Q 4 [ OR (95% CI )=1.33(1.07-1.67), 1.43(1.14-1.80), 1.45( 1.08- 1.95), respectively], and among girls aged 10-17 years in Q 4 group [ OR (95% CI )=1.43(1.04-1.97)] (all P <0.05). Based on the left and right side thresholds (0.36 and 0.46) identified from the U shaped curve among girls aged 7-9 years, WHtR was categorized into low , medium , and high value groups. Without adjusting for BMI, the risks of elevated blood pressure increased in the low and high groups[ OR (95% CI )=2.36(1.44-3.89), 1.48(1.06-2.08)]; after adjusting for BMI, the risk of elevated blood pressure increased in the low group[ OR (95% CI )=2.93(1.76-4.88)] (all P <0.05). Conclusions WHtR is linearly and positively associated with elevated blood pressure among boys aged 7-17 years and girls aged 10-17 years, independent of BMI. Among girls aged 7-9 years, both low and high WHtR are associated with an increased risk of elevated blood pressure, and the risk effect of low WHtR is independent of BMI.