Pre-excitation syndrome is one of the most common clinical arrhythmias and is a type of supraventricular tachycardia. It is mainly due to the fact that during the embryonic development of the heart, myocardial tissue is left behind in the atrioventricular ring structure, which makes the heart’s excitation conduction an additional “bypass”. In rare cases, patients may experience a drop in blood pressure, dyspnea, or even syncope. Treatment of preexcitation syndrome: For patients with preexcitation syndrome who never have tachycardia attacks, they can be suspended without treatment. If tachycardia episodes are frequent with significant symptoms, active treatment should be given. Treatment methods include drugs, catheter ablation, surgery, etc. Drug therapy: The main drugs used are class IC antiarrhythmic drugs (representative drug propafenone, i.e. cardioplegia) and class III antiarrhythmic drugs such as amiodarone, which act on the atrioventricular node and bypass channels. Digitalis drugs such as cetiran, betablockers such as betalactam, and calcium antagonists such as isoptin can shorten the bypass channel inactivity and should not be used. Patients with preexcitation syndrome should be electrically resuscitated immediately if syncope or hypotension occurs during episodes of atrial flutter and fibrillation. Catheter ablation is one of the best measures for the treatment of preexcitation syndrome. The indications are: 1) frequent episodes of tachycardia that are not effectively controlled by drugs; 2) rapid conduction of atrial fibrillation or flutter through the bypass channel with a very fast ventricular rate; 3) failure of antiarrhythmic drug therapy to significantly slow down the ventricular rate during tachycardia; 4) electrophysiological examination showing that the forward conduction period of the bypass channel is shorter than 250 ms during an episode of atrial fibrillation, and drug therapy is usually ineffective. Surgical procedures are now also rarely applied.