In　this　work,　several　measurement　techniques　were　carried　out　to　study　the　effect　of　annealing　on　the　microstructure　and　properties　of　Pt　wires　used　for　the　standard　Pt　resistance　thermometer.　Based　on　analysis　of　the　relationship　within　dislocation　density,　nano-mechanical　properties　and　resistance/resistivity,　the　effect　of　annealing　on　the　resistance/resistivity　of　Pt　wires　was　revealed.　Traditional　techniques　cannot　measure　the　resistance　of　fine　Pt　wires,　and　this　work　proved　a　new　way　to　solve　the　problem.　The　results　showed　that　the　main　impurities　on　the　initial　Pt　wires　were　graphite　and　some　compounds　consisting　of　O,　Ca,　Mg,　Si,　Zn　and　N.　During　annealing,　PtO2　particles　were　formed　near　the　Pt　grain　boundaries　and　some　holes　were　produced　at　the　grain　boundaries.　When　the　annealing　time　was　increased,　the　PtO2　particles　broke　down　into　elemental　Pt　and　O-2　and　some　compound　impurities　decomposed　or　even　disappeared.　Dislocations　were　the　main　affecting　factor　for　the　change　of　nanomechanical　properties　and　resistance/resistivity　of　Pt　wires.　The　dislocation　density　of　Pt　wires　decreased　when　annealing　time　increased,　which　further　led　to　the　decrease　of　hardness　and　resistance/resistivity　of　Pt　wires.