Being able to accurately estimate the intensity of one test on every athlete is a critical task for physical education teachers and coaches in school settings. This is because the tolerant level of every person is different and only important to that person when he/she is under training condition. Thirteen subjects were recruited in this study. The subjects are all basketball players of Kuang Hua Girls Senior School. The experimental procedure includes both exercise measurement and static measurement of electrocardiography (ECG). Firstly, the subject was tested on stair-step test for physical fitness. This evaluates the exercise intensity under steady exercise load. Then a six-minute of static ECG record was also immediately performed on subjects. It evaluates the recovery condition of heart rate. The nine-minute ECG data was recorded without interruption during the experimental stages. The computer program with specific algorithm can calculate the continuous ECG data rapidly. The exercise intensity of subject can also be calculated.