Objective To discuss the causes of abnormal arterial pressure waveforms occurring during coronary angiography(CAG)and percutaneous coronary intervention(PCI).Methods A total of 760 patients,who received CAG and PCI at Nanjing Municipal First Hospital of China from September 2023 to March 2024,were enrolled in this study.The abnormal arterial pressure waveforms were collected,and their morphological features and causes were analyzed.Results A total of 848 abnormal waveforms were recorded,and based on the morphology these abnormal waveforms were classified into 8 types.Three most commonly-seen abnormal waveforms were nested waveform(22.76％,n=193),atypical waveform(21.11％,n=179)and attenuated waveform(15.57％,n=132).The causes of the abnormal waveforms could be classified into 5 categories.The top three reasons were technical operation factors(n=445,52.49％),vascular factors(n=214,25.23％),and individual factors of the patient(n=101,11.91％).In the specific abnormal reasons,the ostial lesions and spasm of the coronary arteries accounted for the largest proportion(n=183,21.57％).Conclusion Accurate identification of abnormal waveforms is essential for the prevention of complications in performing CAG and PCI procedure.The technical operation factors are the main causes for the occurrence of abnormal waveform.