Abstract: The optical signature measurement technology plays an extremely important role in the fields such as missile penetration,optical reconnaissance and operational effect. In order to make better use of infrared radiation characteristics measuring in the optical signature measurement system, it is very necessary to make high-accuracy calibration of the signature measurement system. As requested in developing a certain model ground-based optical signature measurement system, three calibrating methods were discussed and high-accuracy indirect extended source methods were used for calibrating the system. From an overall point of view, the design of tracking and measuring system,blackbody system and large caliber off-axis collimators were explicitly introduced, so the signature measurement system embodied 1 000 mm tracking and measuring facilities,calibration oriented 50-300 ℃ cavity blackbodies as well as 1 100 mm off-axis collimators. Thus the ground-based optical signature measurement system is capable of high-accuracy radiation calibrating and high-accuracy measuring.