Black　phosphorus　has　attracted　broad　interest　because　of　their　low-dimensional　effect,　and　has　become　a　new　kind　of　two-dimensional　(2D)　materials.　Phosphorus　has　several　allotropes.　Black　phosphorus　is　the　most　thermodynamic　stable　in　them.　As　a　kind　of　two-dimensional　materials,　black　phosphorus　has　high　carrier　mobility　and　on/off　ratio.　The　band　gap　of　black　phosphorus　can　be　adjusted　by　its　number　of　layers　from　0.3　to　2　eV.　It　is　of　great　significance　to　the　development　of　new　infrared　and　near-infrared　optoelectronic　devices.　Currently,　the　main　methods　for　preparing　black　phosphorus　are　chemical　vapor　transfer　and　high　energy　ball　milling　methods.　In　this　paper,　black　phosphorus　was　successfully　synthesized　from　red　phosphorus　via　chemical　vapor　transfer　and　high　energy　ball　milling　methods.　Then　black　phosphorus　was　put　in　ethanol　for　10　min　to　liquid　exfoliation,　in　which　the　ultrasonic　power　was　400　W.　The　microstructures　and　stability　of　black　phosphorus　synthesized　by　two　methods　were　characterized　by　X-ray　diffraction　(XRD),　transmission　electron　microscopy　(TEM)　and　differential　scanning　calorimeter　(DSC).　In　situ　electrical　measurements　of　black　phosphorus　prepared　by　chemical　vapor　transfer　were　performed　using　a　commercial　scanning　tunnelling　microscope-transmission　electron　microscope　probing　system　(STM-TEM,　Nanofactory　Instruments)　inserted　into　a　JEOL-2010F　TEM.　The　microstructural　characterization　results　show　that　there　is　some　red　phosphorus　and　amorphous　phases　in　black　phosphorus　prepared　by　high　energy　ball　milling　method.　On　the　contrary,　the　black　phosphorus　prepared　by　chemical　vapor　transfer　method　has　no　amorphous　phases.　The　XRD　results　show　that　black　phosphorus　synthesized　by　chemical　vapor　transfer　method　did　not　change　significantly　after　keeping　in　the　air　for　16　days.　The　DSC　results　show　that　the　volatile　points　of　the　black　phosphorus　prepared　by　high　energy　ball　milling　and　chemical　vapor　transfer　methods　are　respectively　394.5　and　432.2　degrees　C,　which　means　the　latter　has　better　thermal　stability.　The　TEM　results　show　that　a　layer　or　two　layers　of　phosphorene　via　liquid　exfoliation　had　been　obtained,　which　is　large　in　size　and　clean　in　surface.　After　being　irradiated　in　TEM　with　a　dose　of　0.8　eV/(angstrom(2).s)　at　200　kV　for　60　min,　few　new　diffraction　spots　appeared　in　black　phosphorus　synthesized　by　chemical　vapor　transfer　method,　which　indicates　it　is　relatively　stable　under　electron　radiation　in　vacuum.　In　a　word,　the　black　phosphorus　prepared　by　chemical　vapor　transfer　method　has　large　size,　good　crystallinity,　high　purity,　and　high　stability.　It　can　be　used　to　prepare　two-dimensional　black　phosphorus　by　mechanical　exfoliation　and　liquid　exfoliation,　and　then　be　applied　to　advanced　microelectronic　devices.