With　a　bigger　birefringence　than　calcite,　sodium　nitrate　(NaNO3)　single　crystal　might　have　potential　applications　in　fiber-optic　polarizer,　opto-isolators　and　polarizing　prisms.　However,　it　is　difficult　to　grow　large-size　NaNO3　crystals　for　their　thermal　conductivity　anisotropy　and　phase　transition　at　275　degrees　C.　In　this　paper,　crack-free　NaNO3　crystals　with　size　of　Phi　20x100　mm(3)　were　prepared　by　Bridgman　method　with　lower　growth　rate　and　lower　interface　temperature　gradient.　The　dependence　of　the　transmittance　on　the　sample　exposure　time　was　measured　and　studied.　The　principal　refractive　indices　of　NaNO3　crystal　at　the　wavelengths　0.4730,　0.5320,　0.6328,　1.064　and　1.338　mu　m　were　measured　by　auto-collimation　method.　From　which,　we　calculated　and　obtained　the　Sellmeier＇s　equation　of　NaNO3　crystal.　Moreover,　the　photoluminescence　spectra　were　detected　under　the　excitation　at　240　nm,　and　NaNO3　crystal　presented　its　fluorescence　around　416　nm.