Building　better　nuclear　fusion　equipment　with　reduced　cost　is　important　for　a　sustainable　society.　In　this　study,　pure　tungsten　is　deposited　on　different　steel　substrates　by　directed　energy　deposition　(DED).　Specifically,　the　deposited　layers　with　graded　tungsten　content　by　low　and　high　laser　scanning　speed　are　fabricated.　In　addition,　the　processing　parameters　were　optimized　by　analyzing　the　microstructure,　phases　and　defects.　Results　show　that　the　9-layer　sample　(3000　W　@　3000　mm/min)　exhibits　a　better　thermal　performance,　which　the　thermal　conductivity　is　about　73.75　W/(m.K)　at　room　temperature　and　147.45　W/(m.K)　at　900　degrees　C,　respectively.　Finally,　the　surface　of　the　manufactured　thick　deposited　layer　by　high-low　combined　laser　scanning　speed　can　reach　a　high　tungsten　content　of　up　to　99.78　wt%.　It　is　believed　that　the　additive　manufacturing　of　pure　tungsten　by　DED　can　combine　the　advantages　of　tungsten　and　steel　substrates,　and　simplify　the　manufacturing　process　of　thermonuclear　fusion　devices.