The significant uncertainty of absolute spectral responsivity of Standard Transfer Detector in infrared band is difficult to solve, the main factor is measure uncertainty of window transmittance, which is introduced by the state reproduction of Brewster Window. The calibration process and results of Standard Transfer Trap Detector against a Cryogenic Radiometer at 1 064 nm were presented. The novel calibration structure, called Y calibration light path, could effectively eliminate the uncertainty caused by the window reflection loss inside the Cryogenic Radiometer. During the process, the linearity, spatial uniformity, polarization sensitivity and stability of the trap detector at 1 064 nm were measured. It is proved that the Standard Transfer Trap Detector shows a good performance with the uncertainty of absolute responsivity less than 0.023%. The repeatability experimental results show that Y calibration light path reconstruction of cryogenic radiometer is feasible.