Aim To explore the changes of the prevalence rate of blood pressure abnormality in Shanghai Bao-Steel Company-based population. Methods All medical records of the employees were analyzed,who underwent health examination biennially from 1995 to 2002.Systolic blood pressure(SBP) abnormality,diastolic blood pressure(DBP) abnormality and hypertension were diagnosed by SBP≥140 mmHg, DBP≥90 mmHg and SBP≥140 mmHg or DBP≥90 mmHg or administrated hypotensive drugs.SPSS 11.5 of statistical software was used for data analysis. Results During the study period,59 131 person-times received periodic medical check-up,of which 27.1% participants received four times check-up,and 26.6% three times,24.0% twice,respectively.The mean SBP increased from 115.7 mmHg to 123.6 mmHg,and the mean DBP increased from 76.8 mmHg to 83.0 mmHg.The standardization prevalence rates of SBP abnormality and DBP abnormality increased separately from 4.1% and 12.3% to 8.0% and 20.6%.The standardization prevalence rate of hypertension increased from(13.4%) to 23.6% from 1995 to 2000,then decreased to 20.1%.The standardization prevalence rates of SBP abnormality and DBP abnormality of the total increased with time.By the analysis of age and sex,it was found that the prevalence rate of SBP abnormality increased significantly with time in men younger than 60 years old and the prevalence rate of DBP abnormality increased significantly with time in men younger than 50 years old,but the prevalence rates of SBP abnormality and DBP abnormality were so only in women in 40～49 years old.No matter in the total or men or women younger than 60 years old,the prevalence rate of hypertension increased with time from 1995 to 2000,but decreased in 2001～2002.At the same time and the same age range the prevalence rate of blood pressure abnormality in men was higher than that in women.At the same time the prevalence rate of DBP abnormality was higher than that of SBP abnormality. Conclusion The prevalence rates of SBP abnormality and DBP abnormality were increasing in Bao-Steel Company employees,which occured mainly in the middle-age and young men.