Objective:To systematically analyse the blood coagulation features of coronavirus disease 2019 (COVID-19) patients.Methods:An electronic search in PubMed, Scopus, Web of Science, EMbase, and CNKI to collect studies related to the blood coagulation features of COVID-19 patients from 1 January 2020 to 1 May 2020. Two reviewers independently screened literatures, extracted data and assessed the risk of bias of included studies. Then, the platelet count, D-dimer value, prothrombin time (PT), activated partial thromboplastin time (APTT) and fibrinogen of patients with different types of diseases were analyzed by using Stata12.0 software.Results:Thirty-nine retrospective studies involving 6 994 COVID-19 patients were included. The results of meta-analysis showed that:(1) compared with severe group, the platelet count (Weighted mean difference; WMD=20.11, 95% CI 11.53 to 28.69, P<0.001) and APTT (WMD=1.30, 95%CI 0.31 to 2.30, P=0.01) were found to be higher while D-dimer (WMD=-0.41, 95%CI-0.58 to-0.24, P<0.001), fibrinogen (WMD=-0.58, 95% CI-0.76 to-0.39, P<0.001) and PT (WMD=-0.51, 95%CI-0.92 to-0.10, P<0.001) were lower in mild group; the platelet count (WMD=-14.75, 95% CI-29.73 to-0.23, P=0.044) was found to be lower while D-dimer (WMD=1.06, 95% CI 0.65 to 1.47, P<0.001) was found to be higher in critical ill patients. (2)Compared with the survival group, the patients in death group displayed elevated levels of D-dimer (WMD=6.86, 95% CI 4.15 to 9.57, P<0.001) and PT (WMD=1.37, 95% CI 0.73 to 2.02, P<0.001) while platelet count (WMD=-36.40, 95% CI-63.23 to-9.58, P=0.008) remained low. Conclusion:Coagulation dysfunction was common in severe, critical ill and dead COVID-19 patients. Platelet count, D-dimer and PT levels were associated with the severity of the disease, and thus could be used as early warning indicators for the deterioration of the disease during hospitalization.