Temperature variation has influence on the imaging uniformity of an uncooled infrared focal plane. The reason is that the bias of the uncooled infrared focal plane may become unstable after it is affected by temperature variation, resulting in a subtle deviation in the output of the focal plane. Thus, the quality of the image formed by the focal plane is degraded. To solve this problem, a method which uses a FPGA to receive the output feedback from a ADN2850 is proposed. Because the data can be compared with the preset value by using this method, the data difference from the preset value can be corrected continuously. Therefore, the bias circuit can be kept stable and the imaging quality of the infrared focal plane can be improved. This method has the features of high precision and fast response.