This　paper　presents　an　instrumentation　amplifier　for　ECG　signals,　compared　with　the　traditional　three　op　amp　ECG　read　instrumentation　amplifier,　the　circuit　overcomes　the　disadvantage　of　low　common　mode　rejection　ratio　due　to　resistance　mismatch　of　the　three　operational　amplifier.　At　the　same　time,　the　circuit　uses　the　inverting　integral　amplifier　as　an　DC　offset　feedback　circuit　to　eliminate　the　offset　voltage　at　the　input　of　the　amplifier.　This　circuit　implements　the　class-AB　control　circuit　to　achieve　high　linearity　output.　The　circuit　is　compact　with　few　peripheral　components.　The　circuit　is　designed　and　implemented　by　using　0.18　um　CMOS　Technology.　The　circuit　test　results　show　that　the　circuit　can　eliminate　the　input　offset　voltage　of　the　140　mv.　And　has　a　DC　gain　of　40　dB　and　a　common　mode　rejection　ratio　(CMRR)　of　120　dB　at　the　2V　supply　voltage.　THD　is　-64　dB,　and　the　total　input　reference　noise　is　0.78　mu　Vrms,　the　power　consumption　is　121.6　mu　W,　the　bandwidth　is　2　kHz.