Abnormal p-wave on ECG indicates abnormal changes in atrial depolarization potential, which can be seen in arrhythmia, atrial hypertrophy and other diseases. P-wave is an atrial depolarization wave, which can represent the agitation of right and left atria. The front part of p-wave represents the agitation of right atrium, and the back part usually indicates the agitation of left atrium. p-wave is important for the diagnosis and differential diagnosis of cardiac arrhythmia. The p-wave has a fixed size, voltage, morphology, direction, and duration. An abnormal p-wave indicates an abnormal change in atrial depolarization potential, which can be seen in arrhythmia, atrial hypertrophy, pulmonary heart disease, and abnormal serum potassium concentration. It is recommended to go to the hospital to consult a doctor to determine the cause of the abnormal p-wave.