Objectives: In this study, we estimated the impact of COVID-19 on physical activity (PA) for Chinese university students during the pandemic period. Methods: The International Physical Activity Questionnaire was completed online by 1487 students (947 males and 513 females; age 19.72 ± 1.32 years, BMI = 21.12 ± 4.50) from one university in China during the pandemic period, and students retrospectively recalled pre-pandemic PA levels (March 29- April 15, 2020). We analyzed the data using a paired-samples t-test. Results: Overall, COVID-19 produced a 27.89% reduction in total weekly minutes (40.62) of vigorous PA, a 43.38% reduction in total weekly minutes (73.92) of moderate PA, and a 24.36% reduction in total weekly minutes of walking (44.69). Results by sex showed that moderate PA decreased the most, by 47.15% (males) and 37.13% (females), and total PA decreased by 48.29% (males) and 40.18% (females). Conclusions: COVID-19 led to a reduction in PA among Chinese university students. PA decreased more for male than female students. Public policy action might be needed to increase the level of PA of Chinese university students.