The great number of patients presenting to health centers or hospitals during the outbreak of coronavirus disease 2019 (COVID-19) overwhelms the need for critical care support. Early and effective predictors for clinical outcomes are urgently needed for risk stratification. Critically ill patients often develop coagulation disorders, in particular hypercoagulation. Elevated D-dimer is a prominent indicator for the initial coagulopathy of COVID-19. To estimate whether D-dimer is associated with the severity of COVID-19, we performed the analysis of D-dimer abnormalities in patients with COVID-19. The data demonstrated that D-dimer levels were significantly higher in deceased patients than in survivors (weighted mean difference(WMD): 3.70mg/L, 95% confidence interval(CI):1.41–5.98mg/L), and the levels in severe patients were also higher than those in mild cases (WMD: 0.39mg/L, 95% CI: 0.22–0.55mg/L). Therefore, we conclude that elevated D-dimer level is related to the severity and poor prognosis of patients with COVID-19.