Abstract: Objective To analyze the relationship between red blood cell distribution width(RDW) and blood pressure level among children aged 6-11 years,and to provide a reference for effectively preventing and controlling high blood pressure among children of school age.Methods Cluster sampling method was used to select 6 188 school-aged children aged 6-11 years in Guangzhou,and their systolic blood pressure and diastolic blood pressure were measured by blood pressure measurement,while Red blood cell distribution width,hemoglobin,red blood cell count,and hematocrit was calculated by Friedewald equation.Pearson's correlation coefficient and multiple regression were used to analyze the relationship between RDW and blood pressure level.Results The median RDW was 13.3%,and boys(13.4%) got a higher median RDW than girls(13.3%) (Z=8.609,P<0.01).The median systolic blood pressure was 100 mmHg and the median diastolic blood pressure was 64 mmHg.Compared with normotension group,pre-hypertension group and hypertension group had higher RDW levels (H=15.400,P< 0.05).RDW and RBC were positively correlated to systolic blood pressure in Pearson correlation analysis(r=0.044,0.465,P<0.01),while hemoglobin was negatively correlated (r=-0.219,P<0.01).And multiple regression analysis showed that high systolic blood pressure was one of the risk factors of RDW(B=0.002,P =0.008).Conclusion RWD level increased in school-aged children with hypertension or pre-hypertension,and it was positively related to systolic blood pressure.