The cause of preexcitation syndrome type b is due to the presence of an abnormal bypass channel in the right heart. Pre-excitation syndrome develops as a result of a congenital developmental abnormality with the presence of an abnormal electrical conduction pathway between the atria and ventricles, and type b pre-excitation syndrome suggests that the bypass channel is located between the right ventricle and the right atrium. Most patients with preexcitation syndrome have no obvious symptoms and do not require treatment. Very few patients may develop malignant arrhythmias, such as preexcitation syndrome with atrial fibrillation, which may lead to sudden death. Patients with preexcitation syndrome should pay attention to know the symptoms, no symptoms can be temporarily observed, patients with symptoms should go to the hospital in time, to clarify the type of arrhythmia, if necessary, radiofrequency ablation under the guidance of the physician treatment, to avoid recurrent episodes of the disease.