The principle, the method and the experimental system of mid-infrared radiance calibration based on parametric amplification technique were introduced. The equation between different polarization source and its photons per mode was deduced. A high power CW laser stabilized at 532 nm was used to pump a LiNbO3 nonlinear crystal, producing two correlated-photons whose wavelengths were 632.8 nm and 3.34 μm, respectively. The under-calibrated blackbody at 3.34 μm was injected along the direction of the infrared down-converted photons. With the high relativity of the VIS-IR photon pairs, through the measurement of the visible down-converted photons at 632.8 nm, the radiance of the blackbody source at 3.34 μm can be calibrated and 1.53% relative standard uncertainty was reported.