Abstract: OBJECTIVE To investigate the changes and clinical significances of blood brain natriuretic peptide (BNP), procalcitonin (PCT), c-reactive protein (CRP) and interleukin-6 (IL - 6) in patients with chronic heart failure complicated with severe infectious pneumonia, and analyze its clinical value in diagnosis and treatment. METHODS From January 2014 to Hospitalized patients with chronic heart failure complicated with severe infectious pneumonia (infection group), and pure patients with chronic heart failure (uninfection group) from Jan.2014 to Jan.2015 were chosen, with 50 cases in each group, and the plasma BNP, serum PCT, IL-6, and CRP were detected by enzyme-linked immunosorbent method. RESULTS By comparing the immune indexes between infection group and uninfection group, BNP, PCT, CRP, and IL-6 levels of infection group were significantly higher than those of uninfection group (P<0.05). By comparing the immune indexes of patients with different cardiac function classification, cardiac function grade Ⅲ- Ⅳ patients were higher than those of grade Ⅰ- Ⅱ patients (P<0.05). CONCLUSION The blood BNP, PCT, CRP, and IL - 6 levels of patients with chronic heart failure complicated with severe infectious pneumonia were significantly higher following indicators characterized by higher: BNP, PCT, CRP, IL-6, which were closely associated with cardiac disease severity, and increased with the increase of cardiac function classification.