A　report　on　the　polarisation　beam　splitter　with　high-angle-resolved　tunability　in　the　visible　spectrum,　which　was　achieved　in　a　single　layer　of　transparent　thin　film　of　indium-tin-oxide　(ITO).　One-dimensional　grating　structures　were　etched　into　an　ITO　layer　with　a　designed　depth　using　inductively　coupled　plasma,　where　the　remaining　ITO　acts　as　a　waveguide.　Enhanced　reflection　of　light　was　observed　when　the　retro-diffraction　was　overlapped　with　the　waveguide　resonance　mode.　A　beam　splitting　ratio　of　1:1　was　achieved　at　532　nm　at　a　specific　incident　angle.　This　is　a　stable　and　efficient　beam　splitter　with　high　contrast　and　narrow-band　response.　It　can　also　be　applied　as　tunable　narrow-band　filters,　angle　sensors　or　optical　switch.