The　water　gas　shift　reaction　plays　a　crucial　role　in　the　industrial　upgrading　of　hydrogen　sources.　Here,　xPtSm0.8Sr0.2CoO3/KIT-6　(x　=　0.04,　0.18　and　0.51)　was　prepared　via　deposition-precipitation　and　polyvinyl　alcohol-protected　reduction　method.　Among　all　the　samples,　single　atom　Pt　0.04PtSm0.8Sr0.2CoO3/KIT-6　sample　had　the　highest　specific　rate　(10.99　molCO　gPt-　1　h-1)　and　turnover　frequency　(63.2x10-　2　s-1　at　250　degrees　C),　which　was　primarily　attributed　to　the　high　valence　of　Pt　single　atom,　high　Oads/Olat　molar　ratio,　and　outstanding　lowtemperature　reducibility.　The　DRIFTS　demonstrated　the　redox　mechanisms　occur　and　carbonate　as　main　intermediate　over　Pt　single　atom,　while　carboxylate　and　formate　as　intermediates　by　associative　mechanisms　over　Pt　nanoparticles.　By　DFT　calculation,　the　adsorption　energy　of　CO　adsorbed　over　single　atom　Pt　sample　was　much　smaller　than　that　over　Pt　nanoparticles.　This　work　provides　an　effective　approach　to　designing　a　highperformance　catalyst　for　water　gas　shift　reaction.