The infrared radiant track along meridian course (IRRTM) over human body surface was systematically investigated by using the infrared radiation imaging technique. The results demonstrate that it is a normal biological phenomenon appearing in human subjects. The five main characteristics and the condition of its appearance were also summarized. These facts confirm the description of travelling courses of Fourteen Meridians made by the ancients of China and lay a reliable basis for further clarifying the substantiality in relation to meridian course.