Non-destructive testing is one of the important aspects in scientific conservation of cultural relics, where infrared technique has been extensively adopted due to many advantages such as non-intact, non-destructive, high efficiency, wide applicability and safety. A brief introduction about the theory and characteristics of infrared technique is given. By reviewing the latest achievements obtained by infrared photography, infrared spectroscopy and infrared thermography, it shows that infrared technique is very effective in characterizing the image features, internal structures as well as physical and chemical properties of cultural relics. Infrared technique can not only reveal the hidden information about value, technology, pathology and repair history of various types of cultural relics, but also provide qualitative even quantitative reference for their scientific recognition and conservation, which displays a wide prospect in application.