随着开采深度的增加，通风系统变得更加复杂，工作面位置距离地表主扇越来越远，地表主扇供风方式对深部通风的控制力微乎其微，因此有必要将风机安装在井下。风机安装在井下后，极易出现循环风流，要实现高效通风，必须控制循环风问题。复杂矿井循环风流本质是矿井存在漏风，通过分析循环风形成的本质，提出控制通风系统内部循环风流的评价指标，应用自主开发的软件VentNetLab分析得出有效的控制措施，并对极其复杂的通风网络进行实证研究，指导矿山进行整改。

With the increasing of mining depth，the mine ventilation systems become more and more complex， working face location farther away from the main ventilating fan of the earth’s surface than they are used to be，the main ventilating fan of the earth’s surface can not supply much air to the deep of underground.And it could barely control the deep ventilation.Therefore，it is needed to move the fan into the underground.After the fan is installed in the underground，these could have shorten the distance from the ventilation fan to the working face location.However，these have increase more recirculating air.In order to achieve effective ventilation，ensure the deep of underground could get enough air，the problem of the recirculating air must be effectively controlled.Actually the essence of internal air leakage is the existence of the recirculating air in ventilation system.This paper aims to analyze the formation of recirculating air，propose the evaluation indexes of internal air leakage in ventilation system and develop the software-VentNetLab to get effective control measures.And the evaluation indexes-the efficiency of adjustment could be used to evaluate complexity of mine ventilation adjustment. Multi-level stations ventilation must be used by various mine to achieve effective ventilation.This can carry on the research for the extremely complicated ventilation network，and guidance for rectification mine.