Objective: To investigate the correlation between B-natriuretic peptide (BNP) level and cardiac function in patients with chronic heart failure (CHF) complicated with chronic glomerulonephritis. Methods: Patients with chronic heart failure treated in our hospital from June 2013 to June 2015 were selected as the observation object; according to whether it was complicated with chronic nephritis, the patients were divided into CHF group and CHF combined with chronic nephritis group. The renal function and the level of BNP in urinary were observed in two groups. The differences of cardiac function indexes between the two groups were compared, and the correlations between renal function indexes, urinary BNP and cardiac function were analyzed. Results: The level of blood urea nitrogen (BUN), serum creatinine (SCr) and BNP in patients with chronic glomerulonephritis were significantly higher than those in CHF group, while glomerular filtration rate (GFR) level was significantly lower than that of CHF group, and the difference was statistically significant (P<0.05); the levels of right atrial diameter (RAD), left ventricular end systolic diameter (LVESD), left ventricular end diastolic diameter (LVEDD) and left atrial diameter (LAD) were significantly higher than that in the patients with CHF, and the level of LVEF was lower than those in the CHF group, the difference was statistically significant (P<0.05); the level of BUN, SCr, BNP in patients with chronic heart failure combined with chronic nephritis were positive correlated with LAD, RAD, LVESD and LVEDD, and were negative correlated with LVEF, the level of GER was negative correlated with LAD, RAD, LVESD and LVEDD, and was positive correlated with LVEF. Conclusion: The level of urine BNP in patients with chronic heart failure combined with chronic nephritis is high, which is closely related with the heart function index and can be used as a clinical marker.