Based on the uncertainty measurement theory, a thermal comfort level evaluation model for human body in mines is established. With the thermal environment of mines and the special features of human body in mind, ten factors that would influence the thermal comfort of human body are identified, and the uncertainty measurement function is formulated based on the in-situ data and investigation results. The uncertainty influencing factors in the thermal comfort evaluation are determined by qualitative and quantitative analyses, respectively. The entropy weight theory is used to calculate the index weight of these factors and the credibility degree recognition criteria are established to determine the levels. The thermal comfort evaluation is made. This model is used to evaluate the six different stages of a certain copper mine. The results show that the calculation results are consistent with the empirical values of investigations, therefore, the uncertainty measurement method is reasonable and can be applied to the practical engineering. In different depths of mines, different cooling standards should be established for the thermal comfort.