Aim To explore the correlation between cystatin C （Cys C） and the severity of chronic heart failure （CHF）. Methods We selected 925 patients with CHF hospitalized in Shengjing Hospital of China Medical University between February 2009 and January 2012. The database was created and analyzed with SPSS software version 17.0. We analyzed the relativity between Cys C and the severity of CHF with one-way analysis of variance, χ² inspection and Logistic analysis and decided the best critical value of Cys C used as the reference index of moderate and severe cardiac dysfunction with receiver operating characteristic curve （ROC curve）. Results For patients with functional class II-IV ［New York Heart Association （NYHA）］, the density of Cys C is 1.22±0.62, 1.56±0.91, 1.72±1.00 mg/L separately, there is statistical significance in group comparison （P<0.01） in multifactor Logistic analysis, after adjusting many potential influential factors, the OR of Cys C is 2.087 （95%CI: 1.125-3.874） when it is a continuous variable, and 2.335 （95%CI: 1.243-4.385） when it is a binary variable. The best critical value of Cys C used as the reference index of moderate and severe cardiac dysfunction is 1.37 mg/L, when the sensitivity is 95%, the critical value is 0.77 mg/L, when the specificity is 95%, it is 2.57 mg/L. Conclusion The Cys C is an independent risk factor to evaluate the severity of cardiac dysfunction and for patients with CHF, the best critical value of Cys C used as the reference index of moderate and severe cardiac dysfunction is 1.37 mg/L.