A　broad　range　of　terahertz　(THz)　metamaterials　have　been　developed　for　refractive　index　sensing.　However,　most　of　these　metamaterials　barely　make　sufficient　use　of　the　excited　electric　field　which　is　crucial　to　achieve　high　sensitivity.　Here,　we　proposed　a　metamaterial　sensor　possessing　electromagnetically　induced　transparency　(EIT)　resonance　that　is　formed　by　the　interference　of　dipole　and　quadrupole　resonance.　In　particular,　the　strengthening　of　light-matter　interaction　is　realized　through　substrate　etching,　leading　to　a　remarkable　improvement　in　sensitivity.　Hence,　three　kinds　of　etching　mode　were　presented　to　maximize　the　utilization　of　the　electric　field,　and　the　corresponding　highest　sensitivity　is　enhanced　by　up　to　similar　to　2.2-fold,　from　0.260　to　0.826　THz/RIU.　The　proposed　idea　to　etch　substrate　with　a　strong　light-matter　interaction　can　be　extended　to　other　metamaterial　sensors　and　possesses　potential　applications　in　integrating　metamaterial　and　microfluid　for　biosensing.