Abstract: In order to reduce the loss that results from colliery flood, a system dynamics model is established to describe the security level of colliery flood. Based on the model, simulation analysis is carried out under multiple factors. In this way, system dynamic evolution mechanism of colliery flood is revealed. Also, sensitivity analysis is made with respect to the key parameters of the model. Results show that to improve the security level of colliery flood is a long term process. It also finds that, to improve the security level of colliery flood, effort should be made to strengthen the safety management and improve the personnel security level. The proposed method is helpful for safety decision of colliery flood.