Normal people can hold their breath for more than 30 seconds, but the exact duration varies according to individual differences. The length of breath-holding time can indirectly reflect the body’s cardiorespiratory function, clinically there is a simple test of cardiorespiratory function of the experiment for the breath-holding test, the specific method is to let the patient to do a number of deep breaths, and then hold his breath, record the time to be able to hold his breath. It is generally recognized that a breath-holding time of 30 seconds or more is normal, and if the breath-holding time is shorter than 20 seconds, it can be assumed that there may be some problems with the cardiopulmonary function, and it is recommended that further examination be carried out. Breath-holding time can be improved through exercise, such as practicing long-distance running, swimming, sports, or exercising abdominal breathing. Heart disease such as heart failure, or lung disease such as chronic bronchitis can reduce breath-holding time, indicating that the patient’s cardiopulmonary reserve is extremely low. If you experience discomfort in your daily life, it is important to seek medical attention.