The outbreak of 2019 novel coronavirus disease (COVID-19) has posed a grave threat to the global public health. The COVID-19-induced infection is closely related to coagulation dysfunction in the affected patients. This paper attempts to conduct a meta-analysis and systematically review the blood coagulation indicators in patients with severe COVID-19. A meta-analysis of eligible studies was performed to compare the blood coagulation indicators in patients with severe and nonsevere COVID-19. PubMed, Embase, Web of Science, and the Cochrane Library were searched for studies published between 1 December 2019 and 7 May 2020. A total of 13 studies with 1341 adult patients were enrolled in this analysis. Platelet (weighted mean difference [WMD] = -24.83, 95% confidence interval [CI]: -34.12 to -15.54; P < .001), d-dimer (WMD = 0.19, 95% CI: 0.09-0.29; P < .001), and fibrinogen (WMD = 1.02, 95% CI: 0.50-1.54; P < .001) were significantly associated with the severity in patients with COVID-19. The meta-analysis revealed that no correlation was evident between an increased severity risk of COVID-19 and activated partial thromboplastin time (WMD = -1.56, 95% CI: -5.77 to 2.64; P = .468) or prothrombin time (WMD = 0.19, 95% CI: -0.13 to 0.51; P = .243). The single arm meta-analysis showed that compared with the nonsevere group, the severe group had a lower pooled platelet (165.12 [95% CI: 157.38-172.85] vs 190.09 [95% CI: 179.45-200.74]), higher d-dimer (0.49 [95% CI: 0.33-0.64] vs 0.27 [95% CI: 0.20-0.34]), and higher fibrinogen (4.34 [95% CI: 1.98-6.70] vs 3.19 [95% CI: 1.13-5.24]). Coagulation dysfunction is closely related to the severity of patients with COVID-19, in which low platelet, high d-dimer, and fibrinogen upon admission may serve as risk indicators for increased aggression of the disease. These findings are of great clinical value for timely and effective treatment of the COVID-19 cases.