Abstract: For a swing infrared earth sensor (IRES), the characteristics of the chord information from each single channel are given when only two bolometer detectors work. An attitude determination method is proposed using the chord information of the two bolometer detectors, and the bolometer detector redundancy is also discussed. The simulation and experimental results indicate that the attitude determination method is very simple and practicable in engineering application. Meanwhile，the detector redundancy improves the reliability of the IRES.