Objective To detect the blood viscosity values and find out the statistically significant influencing factors of blood viscosity and their fitting formulas among the middle aged and elderly people with high incidence of cardiovascular diseases. Methods The subjects’ blood was collected in the hospital, together with their physiological and pathological information, and LG-R-80 series rotary viscometer detector was used to detect blood viscosity. The statistically significant factors of blood viscosity and their fitting formulas were obtained by using SPSS. Results Blood viscosity increased with age and body mass index (BMI) and reached its peak value in 60 year-old males (5.35 mPa?s) and 50 year-old females (4.45 mPa?s), respectively, then the variation of blood viscosity would be stabilized, with no more increase; the blood viscosity values of males in all groups with different ages were significantly higher than those of females, with difference value in the range of 0.28-0.90 mPa?s; the blood viscosity values were obviously higher in hypertension group than those in normal group, with statistically significant differences (P<0.1). Conclusions The blood viscosity distribution in people with high incidence of cardiovascular diseases has certain regular pattern, and the obtained fitting formula between blood viscosity and influencing factors in this study would provide useful references for further study such as variation of blood viscosity under different physiological conditions, effects of different viscosities on some cardiovascular diseases, and non-invasive detection of blood viscosities.