Black　phosphorus　nanobelts　are　fabricated　with　a　one-step　solid-liquid-solid　reaction　method　under　ambient　pressure,　where　red　phosphorus　is　used　as　the　precursor　instead　of　white　phosphorus.　The　thickness　of　the　as-fabricated　nanobelts　ranges　from　micrometers　to　tens　of　nanometers　as　studied　by　scanning　electron　microscopy.　Energy　dispersive　X-ray　spectroscopy　and　X-ray　diffraction　indicate　that　the　nanobelts　have　the　composition　and　the　structure　of　black　phosphorus,　transmission　electron　microscopy　reveals　a　typical　layered　structure　stacked　along　the　b-axis,　and　scanning　transmission　electron　microscopy　with　energy　dispersive　X-ray　spectroscopy　analysis　demonstrates　the　doping　of　bismuth　into　the　black　phosphorus　structure.　The　nanobelt　can　be　directly　measured　in　scanning　tunneling　microscopy　in　ambient　conditions.