Diabetes　has　been　a　serious　problem　that　poses　threat　to　people＇s　health　all　around　the　world.　It　is　still　a　challenge　for　us　to　detect　blood　glucose　concentration　continuously　and　non-invasively.　In　this　research,　we　developed　a　free-space　spectrum　domain　optical　coherence　tomography　(SD-OCT)　system　for　non-invasive　blood　glucose　detection　which　possessed　advantages　of　easy　construction,　analyzation　and　control.　In　this　system,　a　laser　with　center　wavelength　of　980nm　was　applied　because　of　its　low　absorption　in　both　glucose　and　water,　which　was　suitable　for　OCT　imaging.　However,　the　laser　with　wavelength　of　980nm　was　not　used　in　the　OCT　with　optic　fiber　type　which　was　commercially　designed　for　wavelengths　of　830nm,　1310nm　and　1550nm.　By　applying　a　dispersing　prism,　we　could　obtain　higher　resolution　spectrum　to　acquire　better　OCT　images　and　more　accurate　glucose　concentration.　The　tomography　function　of　this　free-space　SD-OCT　system　was　proved　to　work　by　scanning　onion　sample.　Pristella　maxillaris　is　a　kind　of　fish　with　transparent　body　structure　and　suitable　size,　thus　we　consider　it　to　be　an　ideal　animal　for　blood　glucose　measurement　by　optical　methods.　We　cultivated　pristella　maxillaris,　an　ideal　fish　for　this　experiment,　in　glucose　solutions　with　five　different　concentrations　as　samples　to　study　glucose　monitoring.　The　OCT　signals　of　the　five　groups　correlated　respectively　to　the　glucose　concentrations.　Therefore,　our　method　provided　the　potential　for　measuring　blood　glucose　concentration　non-invasively.