1. There are significant individual differences in resting heart rate of normal adults, with an average of about 75 beats/min (between 60- 100 beats/min). Heart rate may vary with age, sex and other physiological conditions. The newborn's heart rate is very fast, reaching 130 beats/min or more. Among adults, women's heart rate is generally slightly faster than that of men. The same person's heart rate slows down when he is quiet or sleeping, and increases when he is exercising or excited. Under the influence of some drugs or neurohumoral factors, his heart rate will increase. People who often engage in manual labor and physical exercise usually have a slow heart rate. 2. The heart rate of healthy adults is 60 ~ 100 beats/min, most of them are 60 ~ 80 beats/min, and women are slightly faster; Children under 3 years old often exceed 100 times/minute; Older people are slow to respond. When the adult's heart rate exceeds 100 beats per minute (generally not more than 160 beats per minute) or the infant exceeds 150 beats per minute, it is called sinus tachycardia. Common in normal people after exercise, excited, excited, smoking, drinking, drinking strong tea. It can also be seen in fever, shock, anemia, hyperthyroidism, heart failure and the application of atropine, adrenaline and ephedrine. If the heart rate is 160 ~ 220 beats/min, it is often called paroxysmal tachycardia. Heart rate lower than 60 beats/min (generally higher than 40 beats/min) is called sinus bradycardia. It can be seen in athletes who have been engaged in heavy physical labor for a long time; Pathological manifestations are hypothyroidism, increased intracranial pressure, obstructive jaundice, digitalis, quinidine or propranolol overdose or poisoning. If the heart rate is lower than 40 beats/min, atrioventricular block should be considered. Heart rate is too fast to exceed 160 beats/min, or less than 40 beats/min, which is more common in patients with heart disease. Patients often have palpitations, chest tightness and precordial discomfort, so detailed examination should be carried out as soon as possible to treat the cause.