The outbreak of COVID-19 has had a huge impact on the economy of various industries. The volatility of the stock market was exacerbated by the instability of economic activities, which led to the U.S. stock market experiencing four meltdowns in March 2020. Future economic trends are linked to the impact of the epidemic. Therefore, it is reasonable to assess the extent of the impact of the epidemic on the industry. This paper aims to analyze the market changes in the business service industry before and during the epidemic, based on the Fama-French five factor model. Data collected from the Kenneth R. French-Data Library were used to make a multiple linear regression analysis of the business service industry in the US. Data from 2019.3 to 2020.2 have been selected as the data before the epidemic and 2020.3 to 2021.2 as the data during the epidemic. The results indicate that before and during the epidemic, βMKT increased, βSMB was always insignificant. βHML changed from significant to insignificant, and βRMW and βCMA changed from insignificant to significant. After analysis, companies with weak profitability or aggressive investments are worth investing in after the epidemic.