Bias voltage plays a key role in uncooled infrared imaging system.With the birth of the new generation of Infrared focal plane array readout circuit,higher precision,larger adjustable range,more stable bias voltage is required.The principle of bias voltage circuit is introduced at first.The structure of digital potentiometers,operational amplifier controlled by MCU, bias voltage generator,ADC device TLV2544 are introduced to achieve the closed-loop feedback automatic control function.Combined with the computer software,precise adjustment is more convenient.Through testing,four bias voltage outputs range from 0 V to 5.5 V.Accuracy is better than 0.001 V.The system has the features of high stability,quick adjustment and high integration etc,and all performances achieve the desired results.