<p>Radio-frequency energy harvesting is a feasible method for sustainable battery-free operation in wearable electronic devices. Obviously, the performance of the wearable antenna, such as frequency, impedance, etc., will be affected by the human body. However, the impact of the human body on the performance of the fabric-based antenna for energy harvesting is unclear, especially the maximum transmission distance and power conversion efficiency (PCE). Previous studies revealed that the output power of the energy harvesting antenna decreased markedly, while the influence mechanism of the human body lacks research. Given that different positions of the human body present various curvature and medium, this work will systematically analyze the influence of the human body medium, curvature, and antenna–body separation distance on the antenna energy-harvesting performance. The impact of the human body was investigated by examining different positions of the human body, including arm, leg, and chest. The results showed that the maximum transmission distance and PCE of the fabric-based antenna on the arm decreased by 22.4% and 90.1%, respectively. Moreover, the conclusion about the impact of the human body was improved by discussing the curvature and thickness ratio of the human tissue layer in simulation. It has been shown that the shape of the human body has a more significant influence on the antenna resonant frequency. In addition, the performance of the energy harvesting antenna restores to the original values when the distance between the antenna and the human body is 30&#xa0;mm, while the impact of the human body is notable when the distance is shorter than 30&#xa0;mm. The illustration of the effect mechanism of the human body is beneficial to the design of the wearable antenna for energy harvesting.</p>