Abstract: In order to study feasibility of coal-rock interface recognition based on terahertz time-domain spectroscopy, some experiments were taken out by using terahertz time-domain spectroscopy, which used gas coal and sandstone powder tablet as samples. Time delay and attenuation amplitude that caused by terahertz pulse transmission between different samples were obtained. Hilbert-Huang transform was used to make time-frequency analysis of the samples' terahertz spectrum, and the analysis results were compared with the ones by traditional fast Fourier transform method. The comparison results show that resolution of terahertz spectrum is higher in time-frequency domain, and frequency and energy components of terahertz pulse can be analyzed better and more intuitively at any time as well as absorption effect of any frequency at different time. Coal-rock interface recognition process based on terahertz time-domain spectroscopy was introduced. The experimental results show that coal-rock medium can be well distinguished by characteristic value extracted by Hilbert spectrum and marginal spectrum.