The application of terahertz(THz) technique in many fields like petroleum industry requires the high resolution and multifunction to realize the precise detection of different materials. In this study water vapor in atmosphere was scanned with shortand long-path THz spectrometers with different scan ranges. The full width at half maximum of the THz characteristic lines in long-path system reached less than 7 GHz and that in short achieved ~5.5 GHz, indicating that the THz spectroscopy of water vapor can be used to calibrate THz devices. THz systems with right scan ranges could be a promising selection for the identification of solid, liquid and gaseous materials with very similar structures due to the high resolution. The research demonstrates that the multifunctional THz test can be realized through the balance of resolution and sampling space in many fields, such as oil-gas industry. The application of terahertz (THz) technique in many fields like petroleum industry requires the high resolution and multifunction to realize the precise detection of different materials. In this study water vapor in atmosphere was scanned with short and long-path THz spectrometers with different scan ranges. The full width at half maximum of the THz characteristic lines in long-path system reached less than 7 GHz and that in short achieved ~ 5.5 GHz, indicating that the THz spectroscopy of water vapor can be used to calibrate THz devices. THz systems with right scan ranges could be a promising selection for the identification of solid, liquid and gaseous materials with very similar structures due to the high resolution. The research demonstrates that the multifunctional THz test can be realized through the balance of resolution and sampling space in many fields, such as oil-gas industry.