Abstract: In order to estimate the transmission of COVID-19, the asymptomatic class is introduced to the SEIDR model, an improved SEIADR model is proposed to analyze the influence of wearing face masks on the final size and the basic reproduction number of COVID-19.To study the impact of face masks on the transmission of COVID-19, the population is divided into two groups: one group wearing face masks (including susceptible, exposed, infectious, asymptomatic, dead and recovered), and the other not wearing face masks (including susceptible, exposed, infectious, asymptomatic, dead and recovered). The group dynamic model is used to determine the basic reproduction number and the control reproduction number of the epidemic. Then the final size of disease is simulated based on data. Finally, the dynamic influence of face masks on epidemic transmission is simulated by numerical analysis.Data simulations show that without any intervention, the basic reproduction number is 1.35. If 50% of population wear face masks, the susceptibility and infectivity are reduced by 50%, then the control reproduction number will decreased to 0.39, and the final epidemic size will reduce from 73.20% to 16.15%.