A staged transmission model for Corona Virus Disease 2019 (COVID-19) was built based on virus infection dynamics considering prevention and control measures during different periods.The whole country is classified into three level of epidemic areas according to the seriousness of COVID-19,and the number of infected people in each epidemic area is simulated in a staged way.Based on analysis of the simulation results,the impact of measures taken in each epidemic area,such as the traffic control in Wuhan,the counterpart support to Hubei,and the closed community management,on the suppression of virus transmission was further evaluated.The results show that the staged transmission model can well model the changing characteristics of the number of infected people during different periods in each epidemic area.The prevention and control measures practiced by government,such as the traffic control in Wuhan and the closed community management,have significantly inhibited the spreading of COVID-19,indicated by the substantial downward trend in the number of infected people.