As the global demand for energy conservation increases, achieving efficient energy conversion in fans has become a significant challenge in the field of mine ventilation. To investigate the influence of the blade installation angle distribution in the spanwise direction on the energy characteristics of mining counter-rotating axial flow fan, three blade optimization schemes were proposed in this paper. The internal flow field of the fan was obtained by numerical simulation and experimental methods. Based on the entropy production theory, the correlation between energy loss and flow field parameters was established, thus achieving the quantitative assessment of energy loss. The research findings indicate significant differences in energy characteristics before and after blade optimization, with scheme OP1 (when the optimization case 1 is applied to both the front impeller and rear impeller) demonstrating superior performance. Compared to the original fan, scheme OP1 efficiency and total pressure increase by 1.1% and 1.3%, respectively, under 1.0 Q