Objective To observe the characteristics of ambulatory blood pressure in elderly patients with hypertension and explore the factors affecting the circadian rhythm of blood pressure in them. Methods A retrospective study was conducted of the clinical data of a total of 296 eligible elderly hypertensive patients (aged ≥60 years) treated at the Hypertension Clinic of Shanxi Bethune Hospital from January to June of 2021. According to the circadian rhythm of blood pressure, they were divided into a dipper group (n=56), a non-dipper group(n=134), and a reverse dipper group (n=106). The data collected included the general clinical information of the patients, 24 h ambulatory blood pressure monitoring, arteriosclerosis monitoring, 24 h urine electrolytes, and 24 h urine microalbumin detection. SPSS statistics 26.0 was used for data analysis. According to the data type, one-way ANOVA, Kruskal-Wallis H test orχ² test was used to compare the groups. Binary logistic regression was performed to analyze the factors influencing the circadian rhythm of blood pressure. Results Abnormal circadian rhythm of blood pressure (non-dipper group and reverse dipper group) was found in 81.1% of the elderly hypertensive patients, which was significantly higher than that of the normal blood pressure rhythm group (dipper group). The age of the dipper group was lower than that of the non-dipper group and the reverse dipper group [68.00 (65.00,70.00) vs 70.00 (68.00,73.00), 71.00 (69.00,74.00) years], and the differences were statistically significant (P<0.05). The proportion of smokers in the dipper group was lower than that in non-dipper group and reverse dipper group(7.1% vs 39.6%, 47.2%), and the differences were statistically significant (P<0.05). The nocturnal blood pressure drop rate in the dipper group, non-dipper group and reverse dipper group decreased gradually [12.40% (10.70%,14.78%),3.70% (1.58%,5.83%),-4.50% (-8.00%, -2.30%)], and there were significant differences among all groups (P<0.05). The right brachial-ankle pulse wave velocity (baPWV) in the reverse dipper group was significantly higher than that in the non-dipper group and the dipper group[(1 851.57±215.87) vs (1 747.81±244.65), (1 687.00±201.61)cm/s]; the left baPWV in the reverse dipper group was higher than that in the non-dipper group and the dipper group [(1 869.13±232.15) vs (1 758.57±259.18), (1 692.25±205.34) cm/s]; the differences were statistically significant (P<0.05). The 24 h urinary sodium in the reverse dipper group was lower than that in the dipper group[83.00 (59.00,114.75) vs 102.50 (84.00,126.75) mmol/24h]; the 24 h urine microalbumin in the reverse dipper group was higher than that in the dipper group[48.25(36.33,61.64) vs 41.09(32.00,48.94) mg/24h]; the difference was statistically significant (P<0.05). Binary logistic regression analysis showed that age (OR=1.328,95%CI 1.178-1.496; P<0.001) and smoking history (OR=14.953,95%CI 4.706-47.511; P<0.001) were independent risk factors, and 24 h urinary sodium (OR=0.988,95%CI 0.979-0.998; P=0.021) was an independent protective factor of the circadian rhythm of blood pressure in elderly hypertensive patients. Conclusion The incidence of abnormal circadian rhythm of blood pressure significantly increase in the elderly hypertensive patients. Age and smoking history are independent risk factors, and 24 h urine sodium was an independent protective factor of the circadian rhythm of blood pressure in elderly hypertensive patients.