The risk of the epidemic spreading in public health emergency can be understood as the epidemic spreading risk among persons when they touch each other during the movement. Existing methods simplify the effect of persons' movement on the risk of the epidemic spreading and cannot give detail advices to decision-makers. In order to address the above problem, this paper introduces a crowd simulation-based epidemic spread modeling method. Firstly, it describes the epidemic spreading as the crowd moving and the droplet transmission. Secondly, it simulates the epidemic spreading using crowd simulations, traffic simulations and droplet transmission simulations. Finally, it gives three-dimensional virtualizations of the geographical environment, droplet transmission, crowd moving, rich situation and so on according to the level of detail method. The example results of the COVID-19 prevention and control platform of the campus-level unit version and the city-level government version show that the method can give detail advices to decision-makers.