This study aimed to highlight the impact of the COVID-19 pandemic lockdown on emergency department (ED) visits of non-COVID-19 patients in a tertiary hospital and evaluate protocol development during this period.Clinical data of patients who visited the ED of Foshan Hospital of Traditional Chinese Medicine during the first-level response in Foshan, Guangdong province in 2020 (from January 23 to February 24) and the same period in 2019 and 2021 were collected. A retrospective cross-sectional analysis was performed to understand the characteristics of critically ill patients and compare the proportion of hospitalizations, deaths, and emergency ambulance calls (EACs).The number of patients presenting to the ED was significantly decreased, with a 37.75% reduction in 2020 (6196) compared to the same period in 2019 (9954). A rise in patient ED presentations was observed in the same period in 2021 (10,503). This decline was mostly in the 15-45 age group. In 2019, 2020, and 2021, critically ill patients treated by the ED totaled 568 (5.706%), 339 (5.495%), and 590 (5.617%), respectively. Compared to the same period in 2019 and 2021, the proportion of critically ill patients with respiratory system involvement, severe trauma, and poisoning decreased most significantly in 2020 (P<0.05). In contrast, the rates of EACs, hospitalizations, and deaths increased significantly (P<0.05).The number of ED visits to hospitals was decreased during the 2020 lockdown, while the rates of EACs, hospitalizations, and deaths increased significantly though there were no documented COVID-19 cases. Optimizing emergency medical resources and ensuring the safety of healthcare providers and patients were essential to provide efficient emergency diagnosis and treatment during the lockdown.© 2023 Shen et al.