Nanocrystalline　SnO2　thin　films　were　prepared　by　pulsed　laser　deposition　techniques　on　clean　glass　substrates,　and　the　films　were　then　annealed　for　30　min　from　50　to　550　degrees　C　with　a　step　of　50　degrees　C,　respectively.　The　investigation　of　X-ray　diffraction　confirmed　that　the　various　SnO2　thin　films　were　consisted　of　nanoparticles　with　average　grain　size　in　the　range　of　23.7-28.9　nm.　Root-mean-square　surface　roughness　of　the　as-prepared　SnO2　thin　film　was　measured　to　be　25.6　nm　which　decreases　to　16.2　nm　with　thermal　annealing.　Electrical　resistivity　and　refractive　index　were　measured　as　a　function　of　annealing　temperature,　and　found　to　lie　between　1.24　to　1.45　m　Omega-cm,　and　1.502　to　1.349,　respectively.　The　results　indicate　that　nearly　opposite　actions　to　root-mean-square　surface　roughness　and　electrical　resistivity　make　a　unique　performance　with　thermal　annealing　temperature.　The　post　annealing　shows　greater　tendency　to　affect　the　structural　and　electrical　properties　of　SnO2　thin　films　which　composed　of　nanoparticles.