Abstract: In the field of long-distance ventilation, the attenuation law of air supply from the wind duct is of great significance for the air volume regulation and energy saving of the local ventilation system. In order to improve the local ventilation efficiency of the 2201 long-distance transportation roadway in Balasu Coal Mine, and to reduce the safety hazards and energy consumption caused by the air leakage of the wind duct, we study the air leakage problem of the long-distance wind duct. Based on the fluid dynamics and nonlinear seepage theory, the equivalent air leakage area calculation model of wind duct was established, and Fluent software was used to carry out the numerical simulation of wind leakage of long-distance wind duct with the boundary conditions of wind pressure of fan, tunneling length and inlet air volume, to carry out the prediction of the air supply capacity of the working face, and to give the local ventilator air supply scheme for different tunneling length conditions. The study shows that: the current simulation effect based on the theory of equivalent air leakage of the wind duct is better, when the advancing length is 2 000-3 000 m, the length of the wind duct unit is set to 400 m, and the area of equivalent air leakage port is set to 0.003 768 m², the simulation error of wind duct air volume is below 0.4%, and the simulation error of wind pressure is below 5.8%; when the local fan air supply is certain, the wind pressure and the transported air volume are respectively increased with the advancing length and inlet air volume, and the wind pressure and the transported air volume are decreased with the advancing length, and the local fan air supply scheme is given. When the air supply of local ventilation fan is certain, the air pressure and air volume of air transport in the wind pipe show linear and super-linear attenuation respectively with the increase of advancing length, the pressure difference between the inside and outside of the wind pipe leakage and air leakage becomes a quadratic function relationship, and the air leakage rate of 100 metres shows a negative exponential trend with the increase of the length of the wind duct. Based on the study results, the adjustment scheme of fan air supply under different advancing length conditions is proposed, when the advancing length is 3 000-5 000 m, the fan power remains unchanged, and the air supply can be maintained at 650 m³/min; when the advancing length is 5 000-5 500 m, the fan air supply needs to be increased to 700 m³/min; when the advancing length is 5 500-6 000 m, the fan air supply needs to be increased again to 900 m³/min.