Objective To determine the roles of heart rate variability(HRV) in evaluating cardiac autonomic nerve function of patients with vascular dementia. Methods Totally 124 patients with vascular dementia and 102 control subjects received 24h dynamic Holter monitoring to perform frequency domain measures, time domain measures and non-linear analysis of HRV. The following HRV spectral parameters were considered: total frequency power(TF), low frequency power(LF), high frequency power(HF), standard diviation of normal-to-normal intervals(SDNN), square-root of mean squared differences of successive NN intervals(RMSS), and standard deviation of SDNN(SDSD). Poincare plot descriptors included vector angle index(VAI) and vector length index(VLI). Results The time domain measures (SDNN,RMSS,SDSD), frequency domain measures(TF,LF,HF), VAI and VLI were significantly lower in patients with vascular dementia than in control subjects[SDNN:(78±28) vs (129±30) ms, RMSS: (20±8) vs (24±8) ms, SDSD:(17±7) vs (22±8) ms, P＜0.01; TF:(1432±621) vs (1962±583) ms2/Hz, LF:(934±347) vs(1309±371) ms2/Hz, HF:(473±174) vs (601±247) ms2/Hz, P＜0.01; VAI:(0.54±0.14) vs (0.67±0.13) ms, VLI:(154±19) vs (194±25) ms, P＜0.01]. There were less patients who had Poincare scatter grams in shape of comet in patients with vascular dementia than in control subjects. Conclusion We recommend to perform HRV analysis, a noninvasive mehtod, for patients with vascular dementia to evaluate the cardiac autonomic nerve function.