To investigate the characteristic of coagulation function in 303 patients with Coronavirus disease 2019 (COVID-19), we evaluated the correlation between coagulation function and disease status. We retrospectively analyzed 303 patients diagnosed with COVID-19 and evaluated the clinical data of 240 patients who were discharged. The coagulation function of the two groups (mild and severe) was compared. Compared with the mild group, majority of patients in the severe group were male (76.9% vs. 49.8%) and elderly (median age 65 vs. 50), and the proportion with chronic underlying diseases was higher (73.1% vs. 36.1%). There were 209 abnormalities (69.0%) of coagulation parameters in 303 patients admitted to hospital. Comparison of various indexes of coagulation function between the two groups in admission, the proportion of abnormal coagulation indicators in the severe group was higher than that in the mild group (100% vs. 66.1%). The median coagulation parameters in the severe group were higher than those in the mild group: international normalized ratio (1.04 vs. 1.01), prothrombin time (13.8 vs. 13.4) seconds, activated partial thromboplastin time (43.2 vs. 39.2) seconds, fibrinogen (4.74 vs. 4.33) g/L, fibrinogen degradation products (2.61 vs. 0.99) µg/mL, and D-dimer (1.04 vs. 0.43) µg/mL, the differences were statistically significant (p < 0.05). Coagulation dysfunction is common in patients with COVID-19, especially fibrinogen and D-dimer elevation, and the degree of elevation is related to the severity of the disease. As the disease recovers, fibrinogen and activated partial thromboplastin time also return to normal.