Abstract: Zoning ventilation system is used in Sihe Mine currently，which consists of three intake shafts and three return shafts，and the ventilation system is complex.As production continues，many problems have arisen，such as low utilization rate of air volume，greater power consumption，unstable low-voltage power supply of fun in ventilation system of No.1 return shaft，long ventilation distance，large resistance and ventilation capacity near saturation in ventilation system of No. 2 return shaft，the safety and reliability of the whole mine is poor.In order to solve the above existing problems，the ventilation simulation computation network is established by means of ventilation parameters testing，data processing and ventilation system network surveying，and so on.The specific problems of current ventilation system of the mine are analyzed in detail from the aspects of resistance rationality of ventilation system，comparison between supply and demand of air volume in different using places，resistance distribution in the three zones and disturbance of public air intake route to fan working conditions.The ventilation capacity of main air routes （three intake shafts and three return shafts） and the required air volume of each using places are checked.According to the principle that the total air intake should meet the production demand and the total air intake should match the total air return，the optimization and improvement scheme of transforming 3# air intake shaft into return shaft and transforming 1# and 2# return shafts into intake shafts is proposed，that is，the “three intake shafts and three return shafts” ventilation system is transformed into “four intake shafts and two return shafts” ventilation system.The “four intake shafts and two return shafts” ventilation system is re-divided into different sections，and the new ventilation system is adjusted according to the selected optimal partition scheme.The study results show that the final total return air volume reaches 17 743.2 m3/min，the return air volume is increased，the total resistance is decreased，the air volume at each using place meets the requirements，the system resistance distribution is reasonable and the energy consumption of the fan is reduced.

Key words: Mine ventilation, Ventilation system, Zoning ventilation, Computation of ventilation network, Multi-fan complex network, Ventilation resistance, Ventilation optimization