The avian influenza virus (AIV) was diagnosed by measuring the impedance of the biological chip’s electrodes, which was a development direction of the AIV rapid detection. The high precision impedance conversion chip (AD5933) and the ATmega16 MCU were used. Through the circuit design and commissioning, an impedance testing instrument with the energizing frequency range of 1~100kHz was developed. The impedance measurement range was 1~1000kΩ. This impedance testing instrument has capacity to measure one frequency point and sweep frequency testing. To ensure the accuracy of the instrument, a calibration network with 35 different combinations of impedance was used for providing real-time calibration. The BK866(accuracy of 0.2%) impedance testing instrument for adjusting the system can make sure that the testing accuracy of captance was above 3%.