Abstract: The paper elaborated the specific methods of reinforcing and reducing in moxibustion recorded in the literature and probed its mechanism from the perspective of thermodynamics. It holds that reinforcing in moxibustion is to enable the heat transfer rate of smoldering moxa faster than the airflow rate of the combustion zone so as to allow the heat of penetrate into human body. On the contrary， reducing in moxibustion is to enable the airflow rate of the combustion zone faster than the heat transfer rate of rapid burning moxa. As a result， the temperature of the skin surface is lower than that of the upper moxa. Therefore， pathogen could be drained with the intensity of upwards airflow.