On　the　basis　of　laser　structures,　factors　affecting　on　the　beam　quality　were　experimentally　explored　to　improve　the　beam　quality　of　fiber　lasers.　A　hundred-watts　class　all-fiber　laser　with　an　output　power　of　300　W　at　1　080　nm　was　built　when　the　maximum　pump　power　was　436　W.　The　beam　quality(M2)　was　tested,　and　experiments　show　that　the　M2　is　1.13　and　optical-optical　conversion　efficiency　is　69%.　Then,　the　change　of　the　radial　power　distribution　of　the　laser　beam　that　transported　in　a　fiber　was　experimentally　analyzed.　The　result　shows　that　the　cladding　light　power　increases　initially　and　remains　constant　afterwards　as　the　transmission　distance　of　laser　beam　increases　in　the　fiber.　Therefore,　different　beam　qualities　can　be　obtained　after　stripping　the　cladding　light　at　any　selected　transmission　distance.　In　addition,　the　higher　laser　output　power　can　be　obtained　when　the　cladding　light　stripper　is　set　inside　instead　of　outside　of　the　cavity　under　the　same　pumping　conditions.　However,　a　worse　beam　quality　is　left　in　this　case.　Finally,　a　better　beam　quality　M2　at　1.07　is　obtained　by　setting　two　cladding　light　strippers　outside　and　insider　the　cavity,　respectively.