Purpose: This study aimed to examine the levels of physical activity (PA) among children and adolescents in western China, and the influence of parents on their PA, in the era of coronavirus disease 2019 (COVID-19). Methods: This cross-sectional study used a multistage questionnaire to evaluate 4800 children and adolescents of grades 4–12 (9-17 years old) from 48 primary and secondary schools across 16 districts and counties in western China. In addition to PA, questionnaires collected data on demography, family structure, and exercise habits. Data were assessed using the International Physical Activity Questionnaire-Short Form (IPAQ-SF) and analyzed using chi-square tests, t-tests, Spearman’s correlation, and logistic regression models in SPSS.Results: In this study, a minority (42.1%, n=1553) of children and adolescents met the daily exercise target (60 min) recommended by the World Health Organization (WHO). Moderate- to vigorous-intensity physical activity (MVPA) level of boys was significantly higher than that of girls. Regardless of sex, children with the highest MVPA levels were those in grades 4–6, and PA levels decreased with increasing age. Furthermore, for every hour of increase in the daily MVPA of parents, the MVPA also increased by 6.1–13.9 min in children and adolescents. Moreover, areas of higher economic development were associated with lower levels of MVPA.Conclusions: Overall, this study found a low level of MVPA in children and adolescents of western China; both family structure and parental activity have a significant influence on the PA levels. Nevertheless, the impact of COVID-19 on PA levels has not been entirely negative.