In order to obtain material information in the terahertz band，a portable spectrometer in 1 THz- 15 THz was designed in this study. THz quantum cascade laser with wavelength tunable was used as light source，which can emit continuous“white”light in 1 THz-15 THz，and semiconductor of superlattice structure was used as high sensitivity detector in the instrument. The electronics，computer control and data processing system were used to derive the spectral information of the materials，which would reflect the structural information. The terahertz quantum cascade laser bears the advantages of less heat output，less attenuation，high ratio of signal to noise，and wide range. The spectrometer is compact and easy to be moved when it adopts the terahertz quantum cascade laser as a light source. It exceeds conventional spectrometer in many applications.