Objective   To know the status of children's blood pressure and the risk factors of children's hypertension.

  Methods   5 762 children of 7~14 years were sampled by means of whole population random sampling.Blood pressure was measured, the related risk factors were investigated with the uniform questionnaire and hematology indexes were detected.Case control study including 163 cases and control group with a ratio of 1 to 1.Spss 10.0 of statistical software was used for date analysis.

  Results   1.Single factor analysis showed: BM I was risk factor of hypertension(OR=3.16, 95% CI: 1.95-5.11).Analysised SBP and DBP respectively, body mass index(BM I), menarche, white blood cell(WBC), 1ymphocyte(L YM), monocyte(MON)and monocyte percent(MON%)were risk factors of systolic hypertension(OR value were 4.05(95% CI: 2.35~6.97), 3.95(95% CI: 1.69~9.23), 1.98(95% CI: 1.15~3.41), 1.92(95% CI: 1.10~3.33), 3.59(95% CI: 1.69~7.61), 2.33(95% CI: 1.32~4.09)respectively, BMI was also risk factors of diastolic hypertension, OR=2.43(95% CI: 1.52~3.89).2.Multivariate analysis indicated that only BMI could enter the model of hypertension(OR 3.16 95% CI: 1.95 ~5.11);BIM, WBC, MON% could enter the model of the systolic pressure, OR value was 4.56(95% CI: 2.56~8.12), 2.03(95% CI: 1.13~3.65)5.11(95% CI: 1.52~3.89)respectively; Only BMI could enter the model of the diastolic pressure(OR 2.43 95% CI: 1.52~3.89).

  Conclusion   Obese was an important risk factor of child hypertension and it acted on both SBP and DBP.The increasing of WBC and MON% were risk factors of SBP.