Objective Histogram and scatter plot are two important graphical indices for heart rate variability (HRV) analysis which are difficult to quantify the differences between the patients with congestive heart failure and healthy control subjects. This study proposes a new graphical method for HRV analysis, named RR sequence normalized histogram. Methods Firstly, RR sequence normalized histogram was defined. Meanwhile, the index of fuzzy range information entropy (FuzzyRIEn) based on the fuzzy sets was defined. To verify the validity of FuzzyRIEn, a total of 120 subjects (60 patients with congestive heart failure and 60 healthy subjects) were enrolled and the comparison between FuzzyRIEn and the other three indices ［center-edge ratio (CER), cumulative energy (CE) and range information entropy (RIEn)］ that we proposed earlier were analyzed. Results Wilcoxon rank sum test showed that there were no statistical differences in CER (P=0.418), CE (P=0.262) and RIEn (P=0.068) between the two groups meanwhile the difference in FuzzyRIEn (P=0.023) was significant. Conclusions FuzzyRIEn might be valid for detecting congestive heart failure in clinical applications.