When　the　core　size　of　a　holey　microstructural　fiber　is　close　to　the　wavelength,　the　light　propagation　in　the　core　is　greatly　enhanced　and　a　strong　evanescent　field　is　produced　around　the　core.　A　new　air　suspended　core　microstructural　fiber　with　the　core　diameter　of　only　2　μm　is　reported.　The　air　suspended　core　fiber　fabricated　by　sheet-stacking　method　has　large　evanescent　field　and　the　unit　structure　with　micrometer-size　holes.　The　air　suspended　core　fiber,　whose　loss　is　0.16　dB/cm　at　the　wavelength　of　532　nm,　is　very　suitable　for　sensing　detection　of　biochemical　substances.　Using　the　air　suspended　core　fiber　as　sensing　probe,　we　establish　a　simple　fluorescence　detection　system　combining　with　laser　technology,　and　detect　the　fluorescence　properties　of　bioluminescent　labeling　material　CdTe/CdS/ZnS　quantum　dots　with　this　system.　The　limit　of　the　fluorescence　quantum　dots　detected　by　this　system　is　about　1　nmol/L　(corresponds　to　3.78×10　7　quantum　dots),　which　indicates　that　this　system　has　the　properties　of　high　sensitivity　and　rapid　detection　speed.　The　fluorescence　detection　system　based　on　the　air　suspended　core　microstructural　fiber　provides　a　new　method　and　idea　for　the　sensitive　detection　of　biomaterials　marked　by　quantum　dots.　©　2018,　Chinese　Lasers　Press.　All　right　reserved.