The measurement facility based on parametric down-conversion technique is established to measure the quantum efficiency of the infrared analogy detector. Uses the CW laser beam of 2 576.5 nm wavelength tuning out of Optical Parametric Oscillator (OPO) laser as the pump source and the ZnGeP2 crystal as the nonlinear crystal, obtained the correlated photon pairs of 3.42 μm and 10.4 μm. The charge amount of the collected photo-current/voltage signal is converted into the equivalent photon counting, and the dual channel data fluctuation is carried out for the average photon counting of each mode through the method of double light path balance measurement, realized the absolute power responsivity calibrated of an MCT infrared detector at 10.4 μm, the results show a relative combination uncertainty of about better than 4.53% for this calibration method.