China is one of the earliest countries in the world to use coal and jet. However, during the research of unearthed jet cultural relics, it was found that the texture of raw materials of jet cultural relics sometimes deviated from the jet defined in Gemology. Thus, the concept of jet-like cultural relics is advanced in this paper to have jet, lignite, candle coal and other materials which have a similar texture with jet put into the same cultural concept. At present, there is still a large gap in the scientific research on jet-like cultural relics, among which there especially is no scientific judgment method for the most basic study of material type identification. In this paper, 16 pieces of jet-like relics unearthed from Zhouyuan Hejia Cemetery in Shaanxi, Xianyang Yancun Cemetery in Shaanxi, Turpan Shengjindian Cemetery in Xinjiang, and YiliJirentaigoukou Site in Xinjiang are studied for exploring the application of diffuse reflectance Fourier transform infrared spectroscopy in the composition analysis method of jet-like cultural relics. It can be seen through the result of the infrared spectrum that spectrograms of jet-like relics unearthed from different sites are quite different, while spectrograms of jet-like relics from the same site are similar. The infrared spectra are processed by Norris second derivative method for improving the resolution of absorption peak, a special infrared index I=A820 cm-1/A2 870 cm-1 was selected to have the infrared spectra quantitative analysis of different samples. Combined with the density data of some samples, the coalification degree of jet-like cultural relics can be judged preliminarily. Furthermore, the materials of jet-like relics from different sites could be distinguished by the result of principal component analysis, which is consistent with the judgement of the special infrared index. This paper verifies the feasibility of non-destructive analysis method based on the infrared spectrum in distinguishing materials of jet-like cultural relics. In addition, a research method for the identification of jet-like cultural relics’ origin can be provided if enough infrared spectrum of jet ore samples are collected from different areas.