In this paper, we use a novel way to research the piezoresistance coefficients of AlGaN/GaN HEFT affected by the changes of temperatures in the structure of micro-accelerometer. It is shown that saturation current of HEFT would decrease with the increasing temperature, which is about 0.028mA/°C. However, the device can work well at the temperature range of -50°C to 50°C, which indicates that it can work safely in the larger temperature range. Additional we find that the piezoresistance coefficient of HEFT is declined by the simultaneous increase in the temperature.