Thermal comfort is one of the things that a man needs in hot environments. This concept is achieved when the body does not produce heat as much as it loses. Therefore, a thermal equilibrium is created with the environment. It is clear that the human body exchanges heat with the environment in different ways. One of the most important procedures is the evaporation. In hot environments, human body begins to level its temperature in the range of (37±0.5°c) by missing heat and sweating is consequently started. In environments where the temperature is too high, thermal equilibrium of the body can not be achieved through sweating alone. Therefore, cooling systems must be used to obtain the thermal comfort. However, nowadays, due to the energy crisis in the world, it is better to develop the individual ventilation systems instead of using large cooling apparatuses for the thermal comfort. So, the clothing role is very important for individual thermal comfort. In this way, clothing creates micro climate spaces around the body which plays the key role in creating a comfortable. Thus, the main aim of this study is to investigate the effect of air flow on the thermal comfort by reducing the temperature of micro climate. To achieve the mentioned goal, it is necessary to create an environment similar to the human body. So, a device called hot plate was designed and constructed in this regard. The device was able to propose two modes: producing a constant temperature and variable power and/or creating variable temperature and constant energy. The later approach was used in this study that simulates a person's body during moderate to heavy work. Cloth sample used in this experiment was made ??of polyester. In order to simulate the body sweating, a nonwoven fabric containing certain amount of water was used to maintain humidity. In addition, a fan was used to create an air flow with the desired velocity. Results obtained from this study shows that the micro climate between skin and clothing decreases at these conditions, even though a heat is needed for water evaporation. On the other hand, using the governing equations of heat transfer and energy balance method, the temperature loss was calculated in the final. Alpha Key words: Thermal comfort, micro climate, air flow, hot plate, simulation.