Abstract: The key ofthe electrocardiographic method for positioningtips of Peripherally Inserted Central Catheters (PICC) is to get a clear and stable ECG waveform. This paper reviews factors influencing the stability of the ECG waveform which represents the position of the tip of PICC and relevant countermeasures so as to provide guidance for operators adopting the electrocardiographic method to avoid adverse influences caused by these factors in a timely manner,and improve stability of the electrocardiographic method, which aims to promote this technology to better serve the clinical.