Objective To evaluate the effect of haemoconcentration on the prognosis of patients with acute heart failure. Methods 482 patients with acute heart failure treated in our hospital were included. The hemoglobin, hematocrit, albumin, total protein, creatinine and B-type natriuretic peptide (BNP) were measured. And evaluated the prognosis of the difference between haemoconcentration and non-haemoconcentration patients, early haemoconcentration (≤4 d) and late haemoconcentration (＞4 d) patients with the prognosis of the difference. The Cox proportional hazards model was used to assess the correlation between blood concentration and mortality, re-hospitalization of the relevance. Results 185(38.4%) patients developed haemoconcentration, including 84 patients with early haemoconcentration and 101 patients with latehaemoconcentration. Compared with non-haemoconcentration patients, the BNP reduction ［(-319.3±49.4) pg/mL vs.(-196.0±26.3) pg/mL，P=0.004］and body weight reduction［(-2.4±0.5) kg vs. (-1.7±0.3)kg, P=0.008］increased significantly, the difference was statistically significant, suggesting that haemoconcentration in patients with significant signs of congestion reduction. Compared with non-haemoconcentration patients, the incidence of worsening renal function was significantly higher in patients with haemoconcentration(36.8% vs. 27.6%, P=0.035). Cox regression analysis showed that hemoglobin (OR=0.95, 95% CI 0.93~0.98, P<0.001), total protein (OR=0.94, 95% CI  0.92~0.96, P<0.001), albumin (OR=0.93, 95% CI 0.91～0.96, P<0.001)were negatively correlated with the incidence of haemoconcentration during hospitalization. The blood concentration was significantly associated with a 90-day mortality reduction (HR=0.60, 95% CI 0.38~0.96, P=0.013). The late haemoconcentration was significantly associated with a 90-day mortality reduction (HR=0.41, 95% CI 0.19~0.90, P=0.037).