The goal of this research is to develop a Holter ECG system based on Zigbee technique which has a Holter measuring apparatus and a recording apparatus. The Holter measuring apparatus can measure one lead ECG and physical activity status. In order to let patients feeling comfortable, we designed a small size, light weight, and low power apparatuses. The data was storage in the SD card. Moreover, we also proposed a novel method to detect the heart beats in real time. This algorithm can be embedded in a single chip microcontroller. We used the ECG simulator to evaluate the performance of our designed system. In the practical experiment, one person wore this Holter ECG apparatus. The results show our designed Holter ECG system can record the ECG signal and detect the heart beats in real time.