Objective To explore the clinical value of the monitoring of electronic cardiac index (CI) in the evaluation of neonatal congenital heart disease complicated with heart failure. Methods Sixty neonates with congenital heart disease treated in neonatal department from March 1, 2016 to December 30, 2016 were selected, and divided into severe group (n=11), moderate group (n=15), mild group (n=34), and no heart failure group (n=10) according to the modified Ross heart failure score. CI was measured by electronic force measurement. Left ventricular ejection fraction (LVEF) and pulmonary arterial pressure (PAP) were measured by echocardiography. Venous blood sampling was collected to detect the N-terminal type B brain natriuretic peptide (NT-proBNP). Results The neonates in the severe group were mainly under 2-week-old, while those in the mild group and the moderate group were more than 2-week-old. The differences of CI, LVEF, NT-proBNP, and PAP among the groups were statistically different. The CI and LVEF values were lowest in the severe group, followed by moderate group and mild group, and the highest in no heart failure group. The NT-proBNP and PAP values were the highest in the severe group, followed by moderate group and mild group, and the lowest in no heart failure group. Correlation analysis showed that CI was positively correlated with LVEF (r=0.845, P<0.001), and negatively correlated with NT-proBNP (r=-0.886, P<0.001); CI and PAP were weakly negatively correlated (r=-0.595, P<0.001). Conclusions CI reflects the degree of heart failure to some extent and has some clinical value.