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The thermal environment of the development headings in deep underground mines tends to be harsh. The design of a reliable auxiliary ventilation system is an important strategy to maintain the thermal environment and air quality in the workplace. Hence, it is of great significance to comprehensively evaluate the effects of different air supply conditions and explore the optimal solution for the auxiliary ventilation system. In this study, cooling efficiency (CE) and ventilation efficiency (VE), which are the two most widely used indices for evaluating the ventilation in public places, were introduced into the field of underground mine ventilation. Numerical simulations of multiple air supply conditions were carried out to obtain the CE and VE, respectively. A data envelopment analysis model was used innovatively to evaluate and rank the efficiency of the different conditions. In the evaluation model, the air supply temperature and air supply velocity were the inputs, whereas CE and VE were the outputs. The preliminary results showed that cases with either the highest VE or highest CE alone may not actually indicate efficient air supply conditions. The optimum efficiency was determined to be at an air supply temperature difference of 6 °C. Thereafter, the air supply rate could be determined using the psychrometric chart based on the cooling and moisture loads. These results can provide theoretical guidance for optimizing air supply conditions and energy-saving control of mining ventilation and cooling systems.