Objective：This study aims to investigate the clinical effect of sacubitri/valsartan in treating heart failure patients with reduced ejection fraction and to explore the clinical factors of poor treatment of Sacubitri/Valsartan. Methods：A retrospective study of 104 heart failure patients with reduced ejection fraction in the Department of Cardiology，the First Affiliated Hospital of Nanjing Medical University was conducted from December 2017 to December 2018. All patients were treated with sacubitri/valsartan basing on their conventional anti-heart failure drugs for （3.9±2.2） months，6 patients were excluded for withdrawal or death. Baseline population characteristics including sex，age，primary diseases and other basic diseases were described，we also observed the catagories of conventional anti-heart failure drugs and doses of Sacubitri/Valsartan before and after the treatment. NYHA classification，the index of normal vatal signs（HR，SBP），laboratory examinaiton（NT-proBNP），cardiac structure（LVEF，LVDd，LVDs）were compared before and after treatment. The incidence of drug related adverse reactions was recorded. Univarite and multivariate Logistic regression model were applied to analyze the revelant clinical factors influencing the treatment of Sacubitril/Valsartan. Results：①There were statisitcally significant differences in NYHA classification before and after the treatment（P＜0.05）. ② HR and SBP after treatment were statisitcally significant lower than those before the treatment（P＜0.05）；③After treatment，NT-proBNP was significanly less than before（P＜0.05）. ④There were statisitcally significant differences in LVEF，LVDd before and after treatment（P＜0.05），while LVDs did not show the difference（P＞0.05）. ⑤During the treatment of sacubitri/valsartan，three patients withdrew because of severe cough，as well one patient with the increase of serum creatinine；One patient died because of severe valvular heart disease during the treatment，another patient was diagnosed Hodgkins lymphoma and then dead during the follow-up. No one left experienced any obvious hypotension，angioedema or hyperpotassemia.⑥Univariate and mutivariate Logistic regression analysis showed that the length of medical history（OR=4.952）and baseline LVDd（OR=1.124）were related with the poor treatment of sacubitri/valsartan. Conclusion：Sacubitri/valsartan can validly improve NYHA classification，LVEF and decrease NT-proBNP，HR，SBP，LVDd in patients with reduced ejection fraction basing on their conventional anti-heart failure therapy. Clinical factors including the length of medical history and LVDd can influence the treatment of sacubitri/valsartan. With advanced clinical effect and mild adverse reactions，sacubitri/valsartan is recommended for heart failure patients with reduced ejection fraction as early as possible.