We　apply　the　first-principles　calculations　to　investigate　the　structure,　mechanical,　and　thermodynamic　properties　of　WB12　and　TiB12　under　high　pressure　(0-100　GPa).　The　calculated　results　show　that　WB12　and　TiB12　are　thermodynamically　stable　at　the　0　GPa　or　high　pressure.　WB12　is　more　thermodynamically　stable　than　TiB12.　In　particular,　the　calculated　Vickers　hardness　of　WB12　and　TiB12　at　the　ground　state　is　29.9　GPa　and　43.2　GPa,　respectively,　indicating　that　TiB12　is　a　potential　superhard　material.　With　increasing　pressure,　the　calculated　elastic　modulus　of　WB12　and　TiB12　increases　gradually.　The　calculated　electronic　structure　shows　that　the　high　Vickers　hardness　and　elastic　properties　of　WB12　and　TiB12　derive　from　the　3D　network　B-B　covalent　bonds.　In　addition,　the　calculated　Debye　temperature　at　the　ground　state　is　927　K　for　WB12　and　1339　K　for　TiB12,　respectively.　With　increasing　pressure,　the　calculated　Debye　temperature　of　WB12　and　TiB12　increases　gradually.　Our　work　shows　that　TiB12　not　only　exhibits　high　hardness　but　also　shows　better　thermodynamic　properties　in　comparison　with　WB12.