Abstract: The application of terahertz spectroscopy in the identification of energetic material isomers was studied. Firstly, a terahertz time-domain spectrometer for specific engineering application was developed, and its environmental adaptability was verified by vibratory impulse and temperature variation experiments, which indicated the spectrometer could work stably and reliably in a non-laboratory environment. Secondly, the validity of spectrum measurement for the spectrometer was verified by carbon monoxide standard gas, and the calibration of measuring frequency was realized at the same time. The terahertz spectrum of two isomers endo-THDCPD and exo-THDCPD of THDCPD were measured by the calibrated spectrometer. The results show that there are significant differences between terahertz spectrum of two isomers. The terahertz spectrum of endo-THDCPD presents the obvious characteristic absorption at 0.23 THz and 1.70 THz, while the 2 most obvious characteristic absorption peaks of exo-THDCPD are at 1.28 THz and 1.60 THz. Therefore, the use of terahertz spectroscopy can effectively distinguish the two kinds of isomers with only slight difference, which has reference significance for the application of terahertz spectroscopy in the research field of energetic material.