Objectives It is of clinical significance to evaluate the disease severity and investigate possible biomarkers of 2019 Novel coronavirus disease (COVID-19). In this study, we aim to describe the clinical characteristics of infection makers in severe and very severe patients with COVID-19. Methods This is a single center, observational analysis. We enrolled 48 in-hospital severe patients with COVID-19 admitted to the West District of Union Hospital of Tongji Medical College and analyzed infection biomarkers in 20 patients who had been tested for ferritin, PCT, CRP, etc. Results The median age was 59yrd (inter quartile range [IQR]:46-61) among severe COVID-19 group and 57yrd (IQR:45-71.5) among very severe group. We noted significantly increased CRP (1.48mg/L [IQR: 16.69-2.74] vs. 57.98mg/L [IQR: 38.335-77.565], P<0.05), PCT(0.05ng/ml [IQR: 0.03-0.06] vs. 0.21ng/ml [IQR: 0.11-0.42], P<0.05) and ferritin (291.13ng/ml [IQR: 102.1-648.42] vs. 1006.16ng/ml [IQR: 408.265-1988.25]). For blood count, significant increase was noticed in neutrophil percentage (67.6% [IQR: 61.8-76.4] vs. 86.7% [IQR: 82-92.35], P<0.01) and neutrophil count (3.75*10^9/L [IQR: 3.42-4.93] vs. 8.11*10^9/L [IQR: 5.675-8.905], P<0.05); and decrease was seen in lymphocyte percentage (22.7% [IQR: 17.4-27.4] vs. 8% [IQR: 4.85-13], P<0.05), lymphocyte count (1.62*10^9/L [IQR: 0.7-1.73] vs. 0.68*10^9/L [IQR: 0.385-1.04], P<0.05), and platelet count (214*10^9/L [IQR: 184-247] vs. 147*10^9/L [IQR: 126-202.5], P<0.05). Conclusions The serum levels of CRP, PCT and ferritin are markedly increased in very severe compared with severe COVID-19. Increased CRP, PCT and ferritin level might correlate to secondary bacterial infection and associated with poor clinical prognosis.