Abstract: Objective To investigate the correlation between blood pressure variability, circadian arterial blood pressure, pulse pressure index and cognitive impairment in elderly patients with hypertension. Methods Totally 200 elderly patients with hypertension were selected and conducted with simple Mental State Scale for Examination(MMSE). According to the scores, all the patients were divided into control group(n=80, with normal cognitive function)and observation group(n=120, with impaired cognitive function). The effects of ambulatory blood pressure parameters, circadian blood pressure rhythm, pulse pressure index(PPI), left ventricular mass index(LVMI), serum cystatin C(Cys C)and ankle brachial index on cognitive function in elderly patients with hypertension were analyzed. Results There were no significant differences in gender, age, course of disease, body mass index(BMI)and heart rate(HR)between two groups(P > 0.05). The score of MMSE was(28.23±1.14)point in the control group, which was significantly higher than(22.23±3.14)point in the observation group(P < 0.05). The indexes of systolic pressure(SBP), daytime systolic blood - pressure(DSBP), nocturnal systolic blood pressure(NSBP), PP(pulse pressure)and PPI in the observation group were significantly higher than those in the control group(P < 0.05). There were no significant differences in diastolic pressure(DBP), daytime diastolic pressure(DDBP)and nocturnal diastolic pressure(NDBP)between the two groups(P > 0.05). In the observation group, the circadian rhythm ratio was(10.31±4.19)% and carotid intima media thickness(IMT)was(0.85±0.34)mm, which showed significant differences when compared to(16.73±3.85)% and(0.67±0.21)mm in the control group(P < 0.05). There were significant differences in ratios of patients with dipper type and non dipper type between the two groups(P < 0.05). LVMI and Cys C of the observation group were significantly higher than those of the control group, while the ankle brachial index was significantly lower than the control group(P < 0.05). The results of correlation analysis showed that MMSE score was negatively correlated with SBP, DSBP, NSBP, PP and PPI(r=-0.925, -0.867, -0.914, -0.867, -0.927, P < 0.05 or P < 0.01), but showed no significant correlation with DBP, DDBP and NDBP(P > 0.05). Conclusions The cognitive function of elderly patients with hypertension is affected by the circadian arterial blood pressure, LVMI, serum Cys C, pulse pressure index and ankle brachial index. For the elderly patients with hypertension, we should take active and effective measures to control blood pressure and pulse pressure index, prevent abnormal circadian rhythm of blood pressure and reverse atherosclerosis so as to delay the occurrence and development of cognitive impairment.