Abstract: High-altitude mines have low air pressure and low air density, which lead to a significant decline in the performance of fan in high-altitude environments.Based on the basic theory of fan design and the principle of mine ventilation, the effects of high altitude and low air density on the performance of mine axial flow fan and the matching motor power are studied.The reasonable selection method of high altitude mine fan and matching motor is analyzed with examples.The results show that compared with the plain area, the volume flow of the fan in the high altitude area is constant, but the mass flow rate decreases; the pressure of the fan decreases with the decrease of the air density, and the actual pressure is much lower than the sample pressure of the fan selection.When the motor is running, the temperature rise increases, the aging of the insulating material accelerates, and the output power of the motor decreases.