Abstract: With the increase of the mining depth of coal mines, the ground temperature was gradually increasing, and underground micro-climate would produce great influence to human body health and working comfort. In order to evaluate the effect of underground micro-climate on human body comfort, based on the heat balance model, it obtained parameters of different workplaces through the literature research and field investigation, such as temperature, wind speed and so on. Then it calculated and compared the difference value between the human metabolism heat and total heat production under different environmental conditions, which was considered as the evaluation standards of human body comfort, thus it realized the comfort evaluation of different worker types in different workplaces. Finally, it was verified through the test, the comfort of the underground workers was evaluated and some advices were proposed to improve the comfort of the workers.