The normal range of heart rate for a 9-year-old child is 60-100 beats per minute. Heart rate fluctuates with every moment of diet and exercise, and after intense exercise or consumption of spicy and stimulating foods, illness, and major mood swings. Whether the heart rate becomes too fast or too slow, it is abnormal and can have an effect on the heart’s ability to pump blood. It is important to go to the hospital in time to check ECG, cardiac enzymes or cardiac ultrasound to confirm whether there is any abnormality in the body. If the heart rate of 9-year-old children does not exceed 100 beats per minute and there are no abnormalities such as purple lips, panic and chest tightness, there will be no problem. Heart rate and body mass have a great relationship, good body mass will make each time the blood uptake fraction will be lower, the heart rate will be slower, but the intake will be high.