Abstract: The influence of groove depth in one dimensional (1D) subwavelength metal grating on THz spoof surface plasmon ploaritons(SPPs) was theoretically investigateal in detail. Two device geometries were proposed including uniform groove depth 1D metal grating and defect groove depth 1D metal grating. The electric field distribution of metal grating was stimulated by employing COMSOL software. For the uniform structure, the dispersion relation of SPPs propagating along grating can be tailored by groove depth. The metal grating with deeper groove has stronger THz electric field distribution and the spoof SPPs is better confined to grating surface. For the defect structure, electric field distribution characteristics of both sides are determined by the defect groove depth, which can be attributed to reflection and scattering of defect. Based on the proposed theoretical stimulation, the two different subwavelength metal grating structures can provide new functionality for THz wave devices such as wave guiding, attenuator and filter.