Abstract: Objective To examine distribution characteristics,regional clustering status,and influencing factors of blood pressure among residents aged 35-74 years in Qingdao city and to provide evidences for hypertension prevention at individual and population level.Methods Questionnaire survey,physical measurement,and laboratory detection were conducted among 5 095 residents at ages of 35-74 years selected from urban districts and rural towns with multi-stage cluster random sampling.Multilevel model was adopted in analyses on regional clustering and risk factors of hypertension.Results Among the residents,the mean systolic blood pressure (SBP) was 134.34±22.25 mm Hg (135.29±20.90 mm Hg for the men and 133.73±23.06 mm Hg for the women);the mean diastolic blood pressure (DBP) was 82.74±12.11 mm Hg,(83.88±12.16 mm Hg for the men and 82.00±12.01 mm Hg for the women).The overall prevalence rate of hypertension was 48.9% (2 490/5 095) for the residents and the rate of male residents was significantly higher than that of the female residents(52.4% vs.46.6%)(P < 0.01);among the hypertensives,48.2% (1 200/2 490) were hypertension of grade I and 71.0% were newly diagnosed.The results of multilevel analysis showed that the intraclass correlation coefficient(ICC) of SBP at village/community level was 8.01% for the men and 10.24% for the women and the ICC of DBP was 7.06% for the men and 6.07% for the women,suggesting that there was a regional clustering at village/community level for both SBP and DBP among the residents.Age,residential area(urban or rural),smoking,antihypertensive medication,familial history of hypertension,body mass index (BMI),fasting plasma glucose (FPG),and triglyceride (TG) had effects on SBP in the women (all P < 0.05);age,alcohol drinking,antihypertensive medication,BMI,FPG,and high density lipoprotein cholesterol (HDL-C) had effect on DBP in the men (all P < 0.05);age,alcohol drinking,antihypertensive medication,BMI,TG,and HDL-C had effect on DBP in the women(all P < 0.05).Conclusion There is an obvious regional clustering for blood pressure and the level of blood pressure is influenced by various factors (age,residential area,smoking,alcohol drinking,antihypertensive medication,familial hypertension history,BMI,FPG,PBG,TG,and HDL-C) among the residents aged 35-74 years in Qingdao city.