Objective To investigate the physical activity in the elderly patients with chronic kidney disease (CKD) and to analyze the mediating effect of psychological distress on the relationship between physical activity and quality of life. Methods A total of 512 elderly patients with stage 1-3 CKD admitted to Zhongnan Hospital of Wuhan University from January 2020 to January 2023 were selected as the subjects (CKD group). In addition, 120 elderly people who were admitted to the hospital for physical examination were collected as the control group. The international physical activity questionnaire short form Chinese version (IPAQ-S-C) was used to investigate the amount of physical activity in the two groups. Of 632 questionnaires distributed, 598 (94.62%) were recovered as valid, including 490 in the CKD group and 108 in the control group. SPSS 24.0 was used for data analysis. According to the data type, t test, Chi-square test or rank sum test was employed for between-group comparison. The influencing factors of low physical activity in the elderly CKD patients were analyzed by logistic regression analysis. Spearman rank correlation analysis was used to evaluate the correlation between physical activity and quality of life in the elderly CKD patients. Three-step mediating effect test was used to evaluate the mediating effect of psychological distress on the relationship between physical activity and quality of life. Results The physical activity in the CKD group was significantly lower than that in the control group, and the difference was statistically significant (P<0.05). Logistic regression analysis showed that primary school education or below (OR=3.397,95%CI 2.016-5.726), unmarried/divorced/widowed (OR=2.442,95%CI 1.264-4.720), severe fatigue (OR=2.038,95%CI 1.037-4.005) and significant psychological distress (OR=8.265,95%CI 6.001-11.382) were risk factors for low physical activity in the CKD elderly patients(P＜0.05). Three-step mediating effect test showed that psychological distress played a mediating role in the effect of physical activity on quality of life, with a mediating effect of 0.09, and the mediating effect accounted for 26.8% of the total effect. Conclusion Insufficient physical activity is obvious in the elderly patients with stage 1-3 CKD and affect the quality of life, and psychological distress plays a mediating role in it.