Infrared Focal Plane Array (IRFPA) is a key component of the modem infrared imaging system, which consists of readout circuit. The background of IRFPA technology is presented at the beginning of this paper. Then the function of the readout circuit in the signal transmission and the block diagram are described. The characteristics of the CCD readout circuit and CMOS readout circuits are also discussed in this paper. After the discussion of the domestic and overseas status of the readout circuit, the development trend of readout circuit for IRFPA is presented.