Objective To understand the prevalence of respiratory syncytial virus (RSV) and co-positivity of other pathogens before, during and after COVID-19 pandemic, and to provide evidence-based support for improving the prevention and treatment of acute respiratory tract infections (ARTIs) in children. Methods The pathogen detection results of ARTIs children aged ≤16 years who were admitted to the Children's Hospital of Soochow University from January 2016 to May 2024 were retrospectively analyzed. The characteristics of RSV epidemics and mixed positivity for other pathogens in the first year of the COVID-19 epidemic (2020, Stage Ⅰ), the second and third years (2021-2022, Stage Ⅱ) and the post-COVID-19 epidemic (January 2023 to May 2024, Stage Ⅲ) were compared with those in the pre-epidemic period. Results The study included 83356 children with ARTIs, with 11277 (13.5%) testing positive for RSV, 5605 (6.7%) testing positive for RSV alone, and 5672 (6.8%) testing positive for RSV in combination with other respiratory pathogens. In RSV positive children, the detection rates of bacteria, other viral pathogens and atypical pathogens were 39.5%, 13.6% and 5.7%, respectively. RSV test positive rates decreased in 2020 and 2022, while RSV test positive rates increased in 2021, 2023 and 2024 compared with predicted positive rates. There were significant differences in age, epidemic period and season between single RSV positive group and mixed RSV positive group (P<0.001). In stage Ⅲ, the positive rate of RSV mixed with other pathogens was significantly higher than that of single RSV, and the difference was statistically significant (P<0.01). The detection rate of influenza A/B viruses, human parainfluenza virus, adenovirus, human metapneumovirus, Mycoplasma pneumoniae, Chlamydia pneumoniae and Haemophilus influenzae was significantly higher in children with RSV. Conclusions The COVID-19 pandemic had an adverse impact on the prevalence of RSV and the diagnosis and treatment of mixed-positive cases of other pathogens, and the resurgence of mixed-positive RSV and the escalation of infections should be monitored for a long time after COVID-19.