In　the　THz　band,　the　spoof　surface　plasmon　polariton　(SSP)　can　limit　the　light　to　the　designed　specific　spatial　frequency　by　constructing　a　sub-wavelength　structure　on　the　metal　surface.　This　ability　makes　it　possible　to　break　through　the　diffraction　limit　of　THz　imaging.　In　this　paper,　a　one-　dimensional　metal　groove　structure　is　used　to　generate　the　SSP,　and　the　frequency　shift　characteristics　of　the　object＇s　spatial　spectrum　under　the　excitation　of　a　2.52THz　beam　are　analyzed.　On　this　basis,　a　grating-coupling-based　SSP　excitation　structure　is　designed,　which　consists　of　a　combined　array　of　subwavelength　metal　grooves　and　subwavelength　slits　with　different　periods.　This　structure　is　used　to　generate　strong　intensity　and　make　full　use　of　the　incident　beam.　It　is　promising　for　generating　illumination　beams　for　terahertz　far-field　super-resolution　imaging　of　subwavelength-spacing　samples.