The efficacy of infectious disease transmission needs to be based on its basic regeneration index. Currently, the basic regeneration index of new coronavirus is higher than that of SARS, so it can be said that the infectiousness of new coronavirus exceeds that of SARS. As a new disease, new coronavirus has no immunity in the population in general, and everyone is susceptible and easily infected. The incubation period of New Coronavirus also has the ability to spread, and it has a long time to have infectiousness. Moreover, the clinical symptoms of New Crown pneumonia are not typical, and asymptomatic infected persons are also contagious, so New Crown pneumonia is more contagious than SARS.