Endo-tetrahydrodicyclopentadiene (endo-THDCPD) and exo-tetrahydrodicyclopentadiene (exo-THDCPD) are the products of catalytic hydrogenation with cyclopentadiene as the initial reaction of raw material, which are impurities and space isomers. With the widespread application of these two materials in aerospace, aviation and other fields, it is imperative to study its quality evaluation method. The spectral technique is an important means to study the material quality, and a kind of optical-spectroscopy-based endo-THDCPD and exo-THDCPD identification method is developed to improve the detection efficiency of product quality, and it is of great significance to the production and quality control of the respective products. The absorption spectra of endo-THDCPD and exo-THDCPD were measured with NMR, MS, IR, Raman and terahertz spectroscopy (THz) technique at room temperature. The results showed that there were distinct differences of endo-THDCPD and exo-THDCPD in the rest spectra, except that the mass spectrum behavior was basically the same. The difference of the chemical shift of C-1/3, C-5/6, C-7/8 and C-10 is relatively large, and the maximum difference is 10 ppm. It is easy to distinguish the four group of —CH—, they are H-2/4, H-5/6. And the chemical shift of H-5/6 in exo-THDCPD is smaller than that of H-2/4, and the endo-THDCPD is vice versa. The IR spectra and Raman spectra of endo-THDCPD and exo-THDCPD had shown differences both in the frequencies of the vibrational bands and in the relative band intensities. Absorption peaks observing in the terahertz spectra of endo-THDCPD were at 0.24, 0.59, 1.06, 1.71 and 2.53 THz and exo-THDCPD were at 1.41, 1.76, 2.41 and 2.65 THz. It is found that there were more differences in THz. The results can provide basic data for product quality analysis, and also provide experimental references for the application of NMR, IR, Raman and THz to detect spatial isomers.