IR stealth technology is reducing or changing the IR radiation characteristics of the object in order to achieve low detectionable characteristics of the object. It can reduce and absorb the IR radiation energy of the object by improving structure design and applying the principle of IR physics, thus it's difficult for IR detection devices to detect the object. The preliminary research and early development of IR stealth technology was accomplished in the late 1970's. It had important break through and entered the practical period from basic research period. Since 1980, IR stealth technology has been widely applied in the new weapons of foreign army, navy and airforce. At first, the principles of IR stealth are analyzed, then its application and developing tendency are studied.