Objective To investigate heart rate variability (HRV) in coronary heart disease patients undergoing percutaneous coronary intervention (PCI), and to evaluate the impact of type D personality on HRV. MethodsHRV of 412 patients undergoing PCI was measured using dynamic electrocardiogram monitoring for 24 hours. And their demographic and clinical data as well as type D personality were obtained through questionnaire survey. Results The standard deviation of the normaltonormal RR intervals (SDNN) and the mean of the standard deviation calculated over the windowed RR intervals (SDNN index) were significantly lower in patients undergoing PCI than normal values. The SDNN, total power (TP), low frequency (LF) and high frequency (HF) of patients with typeD personality were significantly lower compared with nontype D personality patients (P<0.05, P<0.01). Multiple linear regression showed that type D personality was an independent predictor of SDNN, TP and LF (P<0.05, P<0.01). 〖WTHZ〗Conclusion〖WTBZ〗 HRV of patients undergoing PCI needs to be further improved and it is related to type D personality. More attention and targeted intervention should be provided to patients with type D personality when they undergo PCI, thus to reduce adverse cardiac events.