Objective To explore the relationship between levels of serum hemoglobin and albumin and prognosis of vulnerable period in patients with acute decompensated heart failure with preserved left ventricular ejection fraction(HFpEF). Methods Totally 110 patients with acute HFpEF who were treated in the hospital from December 2016 to December 2019 were selected as heart failure group. Taking whether all-cause death occurred during the vulnerable period (within 3 months after discharge) or the time of re-admission due to heart failure as the prognostic criterion, patients with good prognosis or poor prognosis were classified as the good group (n=72) and the poor group (n=38) respectively, and healthy people who came to the hospital for physical examination during the same period were included in healthy group (n=90). The differences in levels of serum hemoglobin and albumin between heart failure group and healthy group, between the good group and the poor group and the relationship between levels of serum hemoglobin and albumin and prognosis of vulnerable period in heart failure group were compared. Pearson correlation analysis was performed on the relationship between levels of serum hemoglobin and albumin and myocardial injury markers in heart failure group, and the value of the two in predicting the prognosis of vulnerable period was analyzed by receiver operating characteristic curve (ROC).Results The levels of serum hemoglobin and albumin of patients in heart failure group were lower than those in healthy group (P＜0.05), while the levels of cTnI, BNP and CK were higher compared with those in healthy group (P＜0.05). Compared with the good group, levels of serum hemoglobin and albumin were lower (P＜0.05) while levels of cTnI, BNP and CK were higher (P＜0.05) in the poor group. Serum hemoglobin was negatively correlated with cTnI, BNP and CK, and albumin was negatively correlated with cTnI, BNP and CK (r＜0, P＜0.05). ROC curve results showed that the area under the curve, sensitivity and specificity of predicting poor prognosis in patients with acute HFpEF were 0.861, 83.87% and 86.21%when the cut-off value of serum hemoglobin was 129.12 g/L, and were 0.774, 70.97% and 86.21% by taking the cut-off value of serum albumin as 36.49 g/L.Conclusion Low serum hemoglobin and low albumin are risk factors for poor prognosis in patients with acute decompensated heart failure with preserved left ventricular ejection fraction during vulnerable period. The lower their levels, the worse the prognosis of vulnerable period.