Abstract: The spectral responsivity is one of the important parameters of detector. With the development of infrared detection technique, the requirement for infrared detectors becomes higher, so it is necessary to calibrate the absolute spectral responsivity of infrared detectors accurately. The technology to precisely measure the absolute spectral responsivity of HgCdTe detector is investigated. The repeated measurement and calibration for the spectral responsivity of HgCdTe detector were fulfilled by aid of the selfcalibration technology for the relative spectral responsivity of the cavity pyroelectric detector. The average value of the measurement results is given in this paper. The quantity transmission of the absolute spectral responsivity of HgCdTe detector was conducted with the silicon detector calibrated by a cryogenic radiometer. Therefore, the calibration for the absolute spectral responsivity of HgCdTe detector in the fullwave band was realized. At last, the evaluation criterion of the uncertainty, which influences the measurement results, is presented.