As COVID-19 unfolds, it strongly affects individuals, nations from all aspects worldwide, e.g., life quality, country's population, students’ study, household income, GDP, tourist industry. This paper analyzes a detailed analysis from three directions: tourism industry, population, and student academic performance during COVID-19. As for the student performances, four different factors that affect children's academic performance are analyzed. According to the analysis, father's education level, family income, and student achievement are positively significant, whether it is COVID-19 and student achievement are negatively significant. Regarding to country's population, the correlation between COVID-19 new cases and the effect of population, median age, and GDP per capita in each country are estimated. Based on Linear regression model for total cases, it shows the population size and GDP per capita have positive effect on increase in total cases among countries while the median age does not have significant effect. For the last case of tourism industry, data from provinces and states of China as cases are used and linear models on cross-sectional data from 2020 to 2021 are constructed, the findings reveal that the tourism revenue is significantly affected by the number of locally confirmed cases of the COVID-19. Besides, the results also show that the amount of national 5A scenic sites, longitude, and latitude all have a major effect on city tourist revenue, while the COVID-19 pandemic has resulted in a decrease in tourism revenue. Overall, these results shed light on guiding further exploration of investigating the impacts of COVID-19.