Abstract: In order to improve the accuracy of cause analysis of major accidents in coal mines, the existing FRAM system theoretical model is improved by using STEP model to analyze the causes of major accidents in coal mines. The results show that the improved FRAM model has found six critical failure links, including failure links between production tasks and safety production, failure links between maintenance equipment and ventilation, gas monitoring and so on. Finally, the corresponding barrier measures should be made according to the failure connections to ensure the control of major accidents.