Abstract: A multi-level safety evaluation index system covering static and dynamic indicator groups was constructed for the safety assessment and gas dilution capacity research of coal mine ventilation systems,with Chengjiagou Coal Mine as the engineering background.Through fault tree analysis,the reliability of the main ventilation fan system was analyzed,and the system reliability reached 0.982;The failure mode analysis method was used to evaluate the safety risks of the wind network structure,and a three-level warning response mechanism based on online monitoring was established.Differential pressure,wind speed,temperature,and humidity sensors were layered at key locations,and the accuracy of the warning system reached 94.7%.Based on the principle of conservation of mass and concentration diffusion theory,a mathematical model for gas dilution is established,and the segmented integral method is used to deal with gas outburst along the working face.Research has shown that there is a significant nonlinear relationship between working face wind speed and dilution efficiency.The research results can provide theoretical basis and technical support for the safety management and gas control of coal mine ventilation systems.