In　recent　years，with　the　development　of　carbon　dots　in　terms　of　synthesis　routes，reaction　mechanisms，and　optical　properties，a　large　amount　of　work　has　focused　on　carbon　dots　that　emit　long　wavelengths　such　as　infrared　or　near-infrared.　Long　wavelength　refers　to　the　red　or　near-infrared　spectral　region　whose　emission　range　is　600-1　800　nm.　Compared　with　short-wavelength　carbon　dots，they　have　the　characteristics　of　deep　tissue　penetration，less　autofluorescence，long　fluorescence　lifetime　and　less　light　damage，and　can　be　further　applied　in　the　fields　of　biomedical　treatment，optoelectronics　and　optical　device　preparation.　Therefore，in-depth　exploration　of　the　design　and　synthesis　of　long-wavelength　emitting　carbon　dots　is　of　great　significance　for　their　development　and　wide　application.　This　article　reviews　the　research　progress　of　long-wavelength　carbon　dots　in　recent　years，and　introduces　how　to　prepare　long-wavelength　carbon　dots　from　two　aspects：carbon　source　selection　and　control　of　optical　properties.　For　example，choose　some　aliphatic　compounds　containing　more　amino　groups　and　aromatic　compounds　with　conjugated　structures.　And　its　optical　properties　can　be　controlled　through　changing　the　effective　conjugation　length，surface　modification，and　heteroatom　doping.　Finally，the　latest　research　and　future　challenges　of　long-wavelength　carbon　dots　in　some　fields　such　as　biomedicine，LED　optics，encryption　and　anti-counterfeiting　are　introduced.　©　2024　Editorial　Office　of　Chinese　Optics.　All　rights　reserved.