Purpose: To design a measurement system of continuous electrocardiogram (ECG) and to develop a computer program of fast analysis heartbeat. To evaluate the practicability, the three-minute stair-step exercise was tested. Methods: The study contains system design and experimental test. The system design includes hardware circuit, user interface and analysis program. Fifty-one undergraduate students were recruited in the experimental test. Results: The R-wave search program was also suited to the post-exercise ECG data. The accuracy of program executing can be checked by ECG raw data. The characteristic of heart-rate (HR) change was investigated clearly during the recovery period. The data of the subject A showed that the post-exercise recovery period was occurred between 180 second and 200 second. A rapid rise and down of HR was occurred between 215 sec and 240 sec. Conclusion: The recording system of ECG was developed successfully, which including fast algorithm of heart rate calculation. R-wave has the maximal slope and amplitude on ECG signal, and then the differential method was used to locate the R-wave. A threshold was used to be a constrain condition for improvement of R-wave location.