Objective: To examine the association between high body fat mass and elevated blood pressure in children,so as to provide scientific evidence for the prevention and treatment of childhood hypertension. Methods: Participants were recruited from the second follow up survey of the Huantai Childhood Cardiovascular Health Cohort Study conducted in 2021 in Huantai County, Zibo City, Shandong Province, China. A total of 1 266 children aged 10-15 years old were included. The study categorized fat mass (FM), fat mass percentage (FMP), fat mass index (FMI), subcutaneous fat mass (SFM), and visceral fat mass (VFM), respectively, into normal and elevated groups based on age and gender specific median values ( P 50 ) in the study population. The multivariate Logistic regression model was used to analyze the association between the status of body mass and elevated blood pressure. A restrictive cubic spline (RCS) model was used to examine the dose response relationship between the levels of body mass and elevated blood pressure. Results: The detection rates of elevated blood pressure in children with elevated FM, elevated FMP, elevated FMI, elevated SFM, and elevated VFM were all significantly higher than those in the normal group ( P <0.05). After adjusting for all potential covariates, compared to the normal group, elevated FM ( OR =4.51, 95% CI =3.28-6.28), elevated FMP ( OR =4.51, 95% CI =3.28-6.27), elevated FMI ( OR =4.40, 95% CI =3.20-6.12), elevated SFM ( OR =4.52, 95% CI =3.29- 6.30 ), and elevated VFM ( OR =4.48, 95% CI =3.28-6.18) were all positively associated with elevated blood pressure ( P <0.05). The RCS analysis demonstrated that the high levels of FM, FMP, FMI, and SFM showed linear doseresponse relationships with elevated blood pressure ( P non linear >0.05), and elevated VFM was associated with elevated blood pressure in a nonlinear dose response relationship ( P non linear <0.05). Conclusions Children with elevated body fat have a higher risk of elevated blood pressure. There was a dose response relationship between high body mass content and elevated blood pressure in children. It is essential to take appropriate measures to reduce the elevated body fat in children, in order to prevent the occurrence of high elevated blood pressure in children.