The causes of sinus tachycardia in children include physiological causes, medication factors, and pathologic factors, which can be observed, discontinued, and treated for the primary cause. 1. Physiological causes: for example, exercise, nervousness can lead to tachycardia, which is usually transient, can be improved after keeping mood stable and resting, and sedatives can be used if necessary. 2. Drug factors: the application of sympathomimetic drugs such as: epinephrine, isoprenaline, scopolamine drugs such as atropine, scopolamine, scopolamine and ephedrine, etc., the heart rate can be different degrees of rapidity. This kind of situation, stop using drugs will generally improve. 3. Pathological factors: various infections, fever, anemia, hypoxia, dehydration, shock, various heart diseases and hyperthyroidism in older children can increase the heart rate, and the corresponding medication can be selected according to the specific situation. When the above situations occur, consult a doctor in time.