For the past decades, with the frequent occurrence of emergencies, such as stampede, fire, and terrorist attack, the urgent requirements of developing realistic evacuation models to describe pedestrian and disaster dynamics are put forward. In this paper, an extended floor-field (FF) model combined with risk factors is presented for emergency evacuation. A novel dynamic rerouting mechanism is designed to elucidate the exit choice behavior of evacuees, and meanwhile, a recommended dynamic risk-field model is fully explored to deal with dynamical features of disaster. The proposed model is validated through numerical simulations with specific room structures. The effects of model parameters on evacuation efficiency and death toll are analyzed in detail. Simulation results show that the proposed model is effective and has a positive influence on evacuees’ exit choice behavior, and the death toll is closely related to the perceived information obtained by evacuee, such as the crowd density during the evacuation process.