A heart rate of 103 beats per minute may be caused by certain physiologic factors and usually recovers on its own. It may also be caused by fever, infection, arrhythmia, etc., which is usually more serious and requires prompt medical attention to identify the cause. 1, physiological factors: normal adults in a quiet state, the heart rate is generally 60 to 100 beats / min, 103 beats / min of the heart rate may be due to running, heavy physical labor, emotional excitement, etc., usually appropriate rest, adjust the mood can be recovered on their own, without special treatment. 2、Pathological factors: (1) Fever: fever will increase the body’s basal metabolic rate, the body’s oxygen consumption will rise with the rise in body temperature, respiration, heart rate will also be accelerated with the body temperature, so fever can occur in the case of heart rate of 103 beats / min. (2) Infection: Due to the invasion of bacteria, fungi, viruses, parasites and other pathogens into the human body, which causes local tissue or systemic inflammatory reaction, the patient may have an accelerated heart rate, which can also be accompanied by fever, dizziness, chills, chills and other systemic symptoms. (3) Arrhythmia: Due to the change of heart rhythm or heart rate caused by the origin of cardiac agitation or conduction abnormality, patients may also experience different degrees of arrhythmia. More serious arrhythmia can cause palpitation, chest tightness, dizziness, low blood pressure, and in severe cases, fainting or even sudden death. Heart rate of 103 beats per minute, if there is discomfort, rest can not be relieved, it is recommended that patients seek timely medical attention to identify the cause of the disease, and targeted treatment by the doctor.