Spectroradiometry of IR2target-simulators( IRTS) should be calibrated to the standard regularly. There are two ways to calibrate IRTS , one is using IR spectroradiometer and other the IRTS calibration system. Blackbodies are the standard sources for both methods. The former has advantages of convenience and is fit for calibration in situ. The latter is a large instrument and suits for using in lab. By contrasting the collimating radiation , from IRTS and from standard , the calibration system can trace to standard directly. Results of the two methods are showing in the spectrum range 8μm to 14μm and in the order of 10- 10W/ cm2/μm , and analyses to the calibrations are given too.