Objective To observe the effect of sacubitril/valsartan on cardiac function and cardiac remodeling in heart failure with reduced eiection fraction(HFrEF) patients. Methods 120 patients with heart failure with reduced ejection fraction were selected and given standard heart failure treatment according to the 2018 Chinese heart failure guidelines. Regardless of whether the patients had taken ACEI / ARB in the past, they were treated with sakubatravalsartan after admission, starting from the minimum tolerable dose according to the blood pressure. The patients were followed up for 1 month, 3 months, 6 months and 9 months after discharge. During the followup period, plasma NT proBNP level, left ventricular ejection fraction (LVEF), left ventricular end diastolic diameter (LVEDd), left ventricular end systolic diameter (LVESD), left atrial anteroposterior diameter (LAD) were monitored. The 6minute walking distance and the KCCQ score of quality of life scale were recorded, and the adverse reactions were collected. Results After 9 months of followup, the level of plasma NT proBNP was significantly lower than that of baseline, and the decrease was more obvious with the prolongation of treatment time (P＜0.05). Left ventricular end diastolic diameter (LVEDd), left ventricular end systolic diameter (LVESD) and left atrial anteroposterior diameter (LAD) were significantly reduced compared with baseline, and the more obvious the reduction was with the prolongation of treatment time (P＜0.05). Left ventricular ejection fraction (LVEF), 6minute walking distance and KCCQ score were significantly increased compared with baseline, and the increase was more obvious with the prolongation of treatment time (P＜0.05). There were no significant changes in glomerular filtration rate (EGFR) and serum K+ between baseline and baseline. Conclusion Sacubitril/valsartan could improve cardiac function and control cardiac remodeling in heart failure with reduced ejection fraction patients. With the time persistence the effect of Sacubitril/valsartan is incredibly effective and has high safety.