Objective To explore the diagnostic value of procalcitonin (PCT), IL-6 and CRP in sepsis. Methods Forty-five patients with sepsis in Affiliated Hospital of Nantong University, from January 2015 to July 2016 were selected. PCT, IL-6, C-reactive protein (CRP), plasma soluble myeloid cell trigger receptor-1 (sTREM-1), D-dimer, lactic acid (Lac), and Acute Physiology and Chronic Health Evaluation (APACHE II) scores of the patients were analyzed and compared. Univariate and multivariate statistical analyses were performed using unconditional logistic stepwise regression model, and ROC was drawn and the diagnostic efficacy of PCT, IL-6 and CRP for sepsis was compared. Results Age, body temperature, sex ratio, white blood cell count, neutrophil count, neutrophil ratio, platelets, D-dimer and brain natriuretic peptide were not correlated with sepsis severity (P > 0.05); and APACHE II scores, CRP, IL-6, Lac, sTREM-1 and PCT were correlated with the severity of pneumonia (P < 0.05). PCT, APACHE II scores, sTREM-1, CRP, Lac and IL-6 were the independent factors in the diagnosis of sepsis (P < 0.05). The area under the PCT curve was the largest. Conclusions PCT, IL-6 and CRP have high diagnostic value for sepsis and are worth promoting.