The severe impact of the novel coronavirus outbreak in 2019 on human society warns us that large-scale infectious diseases are always the natural enemies of human health. In the process of epidemic prevention and control, virus detection plays an important role, but there are still some problems in the detection strategy, such as the formulation of nucleic acid detection frequency is mainly based on subjective judgment, and there is a lack of quantitative nucleic acid testing frequency research. Therefore, this paper introduces the parameter of detection frequency for the first time, proposes the SEIQR model, takes the epidemic data in Beijing in the normalized epidemic prevention and control stage as an example to analyze, and finds that the SEIQR model can fit the actual data well, which confirms the effectiveness of the 72-hour nucleic acid detection strategy in the normalized epidemic prevention and control stage in Beijing, and provides a new method for the analysis of virus detection effectiveness.