Nuclear　fusion　energy　is　a　clean　and　safe　energy　resource　with　huge　potential.　Tungsten　is　the　primary　candidate　for　plasma　facing　materials　(PFMs)　in　future　nuclear　reactors　because　of　its　high　melting　point,　high　thermal　conductivity　and　high　resistance　to　sputtering　and　erosion.　However,　the　interaction　between　tungsten　and　helium　plasma　generated　by　deuterium-tritium　nuclear　reactions　will　result　in　the　degeneration　of　tungsten　through　helium　blistering　in　tungsten.　The　solubility　of　helium　in　tungsten　is　low,　and　it　tends　to　aggregate　at　grain　boundary,　phase　boundary,　vacancies　and　dislocations,　thus　forming　helium　bubbles.　These　bubbles　will　lead　to　microstructure　changes　of　surface　and　bulk　phases,　as　well　as　a　decrease　in　mechanical　properties,　which　seriously　affects　the　service　life　of　material.　Limited　by　experimental　techniques,　some　basic　problems　for　the　growth　of　helium　bubbles　in　tungsten　are　not　clear,　for　instance,　how　the　helium　clusters　migrate,　and　nucleation　mechanisms.　The　study　of　complex　helium　bubble　formation,　evolution　and　its　underlying　mechanism　in　tungsten　PFM　necessitates　advanced　experimental　techniques.　Traditional　methods　such　as　ion　implantation,　scanning　electron　microscope　and　transmission　electron　microscope　are　inadequate　for　this　task.　Therefore,　we　propose　the　helium　ion　microscope　method　to　investigate　the　aforementioned　several　aspects　of　helium　in　tungsten　in　situ　and　real-time.　Here,　a　helium　irradiation　experiment　is　performed　by　helium　ion　microscope　(HIM),　featuring　nanostructure　fabrication,　ion　implantation　and　microscopic　imaging.　The　HIM　can　generate　an　ion　beam　with　energy　in　a　range　of　0.5-35　keV　and　an　flux　upto　10(25)　ions/m(2)/s.　In　the　process　of　helium　ion　implantation,　we　observe　in　situ　and　real　time　the　helium　blistering　and　the　morphological　evolution　on　tungsten　surface,　in　order　to　capture　the　helium　implantation-induced　microscopic　damage　evolution　on　tungsten　surface　and　subsurface.　From　the　results　of　in　situ　HIM　experiments,　it　is　believed　that　a　strong　orientation　dependence　of　blistering　is　observed　with　the　blister　occurring　preferentially　on　the　surface　of　grains　with　normal　direction　close　to　(111),　and　surface　blistering　of　tungsten　is　directly　related　to　cracks　immediately　below　the　surface.　The　present　study　demonstrates　that　the　HIM　is　a　powerful　tool　for　investigating　the　helium　blistering　behavior　in　tungsten　and　provides　valuable　experimental　data　and　reference　for　designing　PFMs.