Abstract: Objective　To explore the risk factors of subsequent bacterial infection in patients with novel coronavirus disease 2019 (COVID-19). Methods　The clinical data of 136 patients with COVID-19 admitted to Tianjin Haihe Hospital were retrospectively analyzed. According to the results of clinical diagnosis, the patients were divided into two groups: subsequent infection group (44 cases) and non-subsequent infection group (92 cases). The clinical characteristics, treatment and disease outcome of the two groups were compared. The risk factors of subsequent infection were analyzed by Logistic regression. Results　The results of univariate analysis showed that patient age and comorbidity were significantly higher in subsequent infection group than those of non-subsequent infection group (P＜0.01). The proportion of OI＜400 mmHg, hyperthermia (body temperature > 39 ℃), severe cases, acute respiratory distress syndrome (ARDS), hypoproteinemia and cardiac insufficiency were also significantly higher in subsequent infection group than those in non-subsequent infection group (P＜0.05). In the treatment, the proportion of mechanical ventilation, invasive operation, hormone treatment and hospitalization time were significantly higher in the subsequent infection group than those in the non-subsequent infection group (P＜0.05). Logistic regression analysis showed that comorbidity (OR=4.613, 95%CI: 1.756-12.118), hormone therapy (OR=2.403, 95%CI: 1.012-6.422), admission OI＜400 mmHg (OR = 6.534, 95%CI: 2.064-20.691), hypoproteinemia (OR=12.949, 95%CI: 3.284-51.067) were independent risk factors for subsequent bacterial infection. Conclusion　The subsequent infection of COVID-19 patients is closely related to OI＜400 mmHg, hypoproteinemia, hormone therapy and comorbidity. Early clinical intervention can prevent subsequent infection in patients and help improve prognosis.