Abstract: In order to monitor ECG ( Electro Cardio Gram) signal of sub-healthy people in a real-time，the research used the integrated chip of ads1191 to collect two heart signals ( ＲA and LA) ，which was transmitted to the MSP430F2132 via SPI ( Serial Peripheral Interface) and then to the computer by bluetooth technology． The required heart rate was obtained by using low-pass filter to eliminate interference signal，and using the second order difference method to monitor the position of Ｒ wave in the ECG waveform． Instead of using lead wire between Electrode patch andelectrocardiograph，this research avoids interference caused by it effectively，and meets the needs of daily wear for its smaller size and lower power． Under the battery power supply of 1 000 mAh，the system can work continuously for 48 h，ensuring the normal data transmission within the range of 3 ～ 4 m．

Key words: medical equipment, dynamic electrocardiograph, serial peripheral interface ( SPI ) , bluetooth technology, second-order difference, no lead wire