This paper presents a low power-low voltage operational transconductance amplifier (OTA) which is designed for instrumentation amplifier and low pass filter application. In addition, an ECG measurement system has been built based on the proposed circuitry with a bias voltage of 0.9V, and power consumption of only 106.2uW. The system is fabricated with a 0.35μm 2P4M CMOS technology, and the signal processing bandwidth is 0.05Hz~45Hz.