Objective To investigate the effects of human milk fortifier on premature infant's cardiac function.Methods From January 2014 to December 2016, sixty premature infants of paediatric preterm infants were selected from Daqing Longnan Hospital,Heilongjiang province. The random number table method was divided into 30 cases (milk feeding and strengthening agent) and the control group of 30 cases (pure milk feeding).The heart rate of premature infant was measured before, during and after using human milk fortifier. After using human mike fortifier for 1 week, heart rate, electrocardiogram (p-wave duration, QRS wave duration, P-R interval, incidence of arrhythmia), echocardiogram (LVEF, RVEF, E/A ratio of mitral and tricuspid valves) and myocardial enzymes (the quantity of AST, LDH, CK and CK-MB) were compared between experimental group and control group.Results The heart rate of premature infant during using human milk fortifier was significantly faster than those before and after using human milk fortifier and that of children in the control group (P<0.05). There were no statistically significant differences in electrocardiogram (p-wave duration, QRS wave duration, P-R interval), the systolic and diastolic function of the heart and myocardial enzymes between the experimental and control groups (P>0.05).Conclusions Human milk fortifier can increase the heart rate of premature infant, and has no harmful effect on cardiac electrical activity, pump function and myocardial enzymes.