Abstract: The absorption spectra of pyrotechnics oxidants of KClO<sub<3</sub<, KClO<sub<4</sub< and KNO<sub<3</sub<, in the frequency range between 0.2 and 2.5 THz, are calculated using quantum chemistry method. The experimental result obtained from THz time-domain spectroscopy system gives the detailed localities of the characteristic peaks of concerned oxidants. The experiment also provides the absorption spectrum of pyrotechnics which contains KClO<sub<4</sub< between 0.2 and 2.5 THz. The characteristic peak of KClO<sub<3</sub< is located at 2.4 THz. The characteristic peaks of both KClO<sub<4</sub< and pyrotechnics which contain KClO<sub<4</sub< are located at 2.0 and 2.2 THz. The characteristic peaks of KNO<sub<3</sub< are located at 1.8 and 2.3 THz. Compared with experiment results, all the evidences indicate that KClO<sub<3</sub<, KClO<sub<4</sub< and KNO<sub<3</sub< have distinct characteristic spectroscopic peaks, which agree with the results of analog calculation.