Indium　tin　oxide　(ITO)　films　with　high　visible　transmittance　were　fabricated　on　polymethyl　methacrylate　(PMMA)　flexible　substrate　at　room　temperature　by　radio　frequency　(RF)　magnetron　sputtering.　The　deposition　rate,　microstructure,　surface　roughness,　electrical　and　optical　properties　of　these　films　have　been　investigated　as　a　function　of　Ar　partial　pressure　from　0.2-1.4Pa.　The　microstructure　and　surface　morphology　of　ITO　films　were　studied　using　X-ray　diffraction　(XRD)　and　atomic　force　microscopy　(AFM),　the　resistivity　was　investigated　by　four-point　probe　technology,　and　the　optical　transmittance　was　determined　by　UV-Vis　spectrophotometer.　The　results　show　that　the　resistivity　of　the　ITO　film　decreases　with　increasing　Ar　partial　pressure　from　0.2Pa　to　0.8Pa,　and　then　increases　with　increasing　Ar　partial　pressure　from　0.8Pa　to　1.4Pa.　The　resistivity　varied　from　1.25x10(-3)　Omega.cm　to　2.33x10(-3)　Omega.cm　and　the　average　transmission　in　the　visible　range　was　90%.　It　was　also　found　that　the　microstructure　is　amorphous　and　the　surface　roughness　decreases　from　1.438nm　to　0.813nm　with　increasing　Ar　partial　pressure　to　1.1Pa.　The　most　interesting　fact　is　that　the　resistivity　increases　with　the　increasing　surface　roughness,　which　indicates　that　the　surface　roughness　also　plays　an　important　role　in　electrical　properties　of　the　ITO　films.　(C)　2012　Published　by　Elsevier　B.V.　Selection　and/or　peer　review　under　responsibility　of　Chinese　Vacuum　Society　(CVS).