Online teaching plays a vital role in ensuring the teaching order of all kinds of schools during the prevention and control of COVID-19 epidemic in 2020.However,what is the impact of the large-scale application of online teaching on teaching quality during the epidemic prevention and control period is an unanswered question.Based on the investigation of the empirical evidence of a 9-year school called D in Hubei Province,this paper points out that long-term online teaching has a significant negative impact on the teaching quality of primary sch...