The difference between sinus tachycardia and supraventricular tachycardia should be identified from the following points. 1. origin, the place of origin of the excitation of sinus tachycardia is the sinus node, and the morphology of the P wave is sinus. The heart rate is easily affected by respiration, emotional excitement, exercise, rest and other factors. The symptoms of supraventricular tachycardia are more severe and may be accompanied by anxiety, dizziness or even syncope, angina pectoris, heart failure, shock, etc. The heart rate during an attack is not affected by factors such as exercise and breathing. 3. heart rate, the heart rate of sinus tachycardia is 100-150 beats per minute, and the heart rate gradually accelerates and decreases during an attack. The heart rate of supraventricular tachycardia is 150-250 beats per minute, which is sudden onset and sudden stop. 4, ECG, the P-QRS-T wave pattern of sinus tachycardia is normal, only the RR spacing is shortened. The QRS-T wave morphology of supraventricular tachycardia is normal, but the P wave is inverted in leads II, III, and AVF. It is usually triggered out by atrial precontraction.5. Relief mode, stimulation of the vagus nerve during sinus tachycardia, such as massage of the carotid artery and sinus-induced nausea, can gradually slow down the frequency of the attack, but it accelerates to the original level again after stopping stimulation. Stimulation of the vagus nerve during an attack of supraventricular tachycardia can sometimes terminate the attack, but it may also be ineffective.