To analyze motion artifact\'s affect on HRV measures, the age/gender related autonomic changes were investigated by using different HRV measures from wearable medical devices under ambulatory home-monitoring condition. Twelve healthy undergraduates and 20 healthy elderly subjects participated in the research. The electrocardiogram data was collected by using waist-worn device developed by us. Ten HRV measures were used to analyze the age-related automatic change including linear and nonlinear HRV indexes. Many linear HRV indexes were seriously contaminated by motion artefact, and did not reflect the age-related autonomic change. The approximate entropy (p < 0.001) was the best indicator among 10 HRV indexes. However, the approximate entropy was also contaminated by motion artefact and did not reflect the gender-related autonomic change. The study verified the hypothesis that the HRV measures could be contaminated under ambulatory monitoring condition. It is importance for ambulatory home-monitoring to study the robustness of HRV measures.