Purpose: The purpose of this study was to determine the effects of different intensity of aerobic exercise for four weeks on cardiovascular risk factors, reactive oxygen, and antioxidant enzymes in old mice. Methods: Eighteen male C57BL/6 mice age 18 months were randomly classified into the control group (n=6), the moderate intensity exercise group (n=6), and the low intensity exercise group (n=6). The training groups performed the aerobic exercise twice daily for 20 minutes, five days weekly for four weeks. Data were analyzed using descriptive statistics, analysis of variance (ANOVA), the Chi-square test, and the Tukey’s test with the SPSSWIN 21.0 program. Results: In this study, among the risk factors of cardiovascular disease, blood sugar (BS) (p=.023) and total cholesterol (TC) (p=.001) were significantly different between the moderate intensity exercise group and the control group. Additionally, there were significant differences in the reactive oxygen malondialdehyde (MDA) (p=.001), the antioxidant enzymes superoxide dismutase (SOD) (p<.001) and glutathione reductase (GR) (p=.015) between the moderate intensity exercise group and the control group. Conclusion: This finding suggests that moderate intensity aerobic exercise promotes the activity of antioxidant enzymes and lowers cardiovascular risk factors in older mice.