The　intrinsic　kinetics　and　mechanism　of　direct　dehydrogenation　of　isobutane　were　studied　over　K-Cu-Cr/Al2O3　catalyst.　The　experiments　had　been　carried　out　in　a　fixed-bed　reactor　with　eliminating　the　influence　of　both　internal　and　external　diffusion　at　470-510　degrees　C　and　space　velocity　of　2500-4000　h(-1)　under　atmospheric　pressure.　Based　on　the　Langmuir-Hinshelwood　mechanism,　the　intrinsic　kinetics　models　were　established,　and　they　were　verified　by　statistical　analysis.　The　parameters　in　the　models　were　estimated　by　using　the　method　of　Simplex-Method　(SM)　combined　with　General　Global　Optimization　Algorithm.　The　results　of　the　kinetics　modeling　showed　that　the　rate-determining　step　was　the　surface　reaction　process,　which　was　the　best　one　to　describe　the　experimental　data.　The　activation　energy　of　dehydrogenation　reaction　was　obtained.　And　the　models　can　provide　an　important　basis　for　the　design　of　industrial　reactor.