Objective To investigate the correlation between parameters of ambulatory blood pressure and mild cognitive impairment (MCI) among the elderly. Methods A total of 306 retired cadres who had finished the annual health examination at Changhai Hospital from March to July in 2020 were enrolled as the research subjects. Their general data, results of laboratory tests, and medical history were collected. Portable ambulatory blood pressure monitor was used to record the average blood pressure, standard deviation of blood pressure, variation coefficient of blood pressure, morning blood pressure surge and circadian rhythm at the different time intervals. Montreal cognitive assessment (MoCA) was employed to evaluate the cognitive function. According to the results, the subjects were divided into MCI group (n=218) and the normal cognition group (n=88). SPSS statistics 26.0 was adopted for data analysis. Student′s t test, Mann-Whitney U test, or Chi-square test was performed for intergroup comparison depending on data type. Spearman rank correlation analysis was conducted to analyze the correlation of ambulatory blood pressure and MCI. Multivariate logistic regression model was established to analyze the influencing factors for MCI. Results Compared with the normal cognition group, higher average blood pressure, standard deviation of blood pressure, variation coefficient of blood pressure, and circadian rhythm were observed in the MCI group (P<0.05). Correlation analysis indicated that the total MoCA score was negatively correlated with 24-hour mean systolic blood pressure, daytime mean systolic blood pressure, night mean systolic blood pressure, 24-hour mean systolic blood pressure standard deviation, daytime mean systolic blood pressure standard deviation, night mean systolic blood pressure standard deviation, daytime mean diastolic blood pressure standard deviation, 24-hour mean systolic blood pressure coefficients of variation, 24-hour mean diastolic blood pressure coefficients of variation, daytime mean systolic blood pressure coefficiens of variation, night mean systolic blood pressure coeffients of variation, and night mean diastolic blood pressure coeffients of variation (r=-0.151, -0.144, -0.136, -0.202, -0.253, -0.158, -0.253,-0.210, -0.190, -0.220, -0.178, -0.119; P＜0.05), and positively correlated with 24-hour mean diastolic blood pressure, daytime mean diastolic blood pressure, and night mean diastolic blood pressure (r=0.163,0.157,0.138; P＜0.05). Multivariate logistic regression analysis showed that age, 24-hour mean systolic blood pressure coeffients of variation, non-dipper and reverse-dipper in the circadian rhythm (B=11.000, OR=1.115, P<0.01; B=0.270, OR=1.305, P<0.01; B=1.496, OR=4.646, P<0.01; B=1.306, OR=3.690, P<0.05) were independent risk factors for occurrence of MCI among the elderly. Conclusion Ambulatory blood pressure variability is closely associated with the occurrence of MCI among the elderly. Controlling abnormal blood pressure variability may be beneficial in preventing the occurrence of MCI.