Background: November 2022, a large number of Omicron infections suddenly appeared in Beijing, but the epidemiological and clinical characteristics of the epidemic cases are unknown. Methods: We collected the data of COVID-19 cases in Fangcang hospital in Beijing from November 20, 2022 to December 8, 2022, and analyzed the epidemiological and clinical characteristics. We used descriptive statistical methods to explore the basic characteristics, used parametric distribution to calculate the time to events, and used ArcGIS to explore the distribution patterns of COVID-19 cases in different areas. Results: There were 1,307 COVID-19 cases in the Fangcang shelter hospital enrolled the study, among which 85.9% were asymptomatic and 14.1% were mild. Epidemiological data showed that the transmission speed Omicron variant is fast and the transmission range is wide, large-scale infections have occurred in both rural and urban areas, and all age groups are susceptible to Omicron variant. In addition, antipyretics and cough drugs were the two most commonly used drugs, because 51.3% and 22.7% patients had fever and cough, respectively, and 10.3% patients took hypnotics. Furthermore, the proportion of patients with chronic diseases was low (13.9%), while the vaccination rate (71.2%) was relatively high. Conclusion: Based on the results of Fangcang shelter hospitals, we found that most mild and asymptomatic cases did not need treatment, which indicates that home isolation is correct and feasible. However, the transmission speed Omicron variant is fast and the transmission range is wide, and all age groups are susceptible to Omicron variant; therefore, the awareness of prevention and control should not be relaxed.