A　method　for　a　laser　additive　manufacturing　based　on　the　keyhole　effects,　　comprising　placing　a　welding　wire　and　a　laser　beam,　　at　a　certain　angle,　　on　both　sides　of　the　normal　line　of　a　substrate,　　the　laser　beam　is　applied　on　the　welding　wire　to　generate　a　deep　penetration　keyhole,　　the　welding　wire　absorbs　the　laser　energy　so　as　to　be　heated　and　melted　in　a　deep　penetration　mode　and　transits　to　a　surface　of　the　substrate　to　form　a　cladding　layer;　　the　laser　beam　irradiating　the　substrate　surface　after　passing　through　the　filament,　　and　preheating　the　substrate　surface　in　a　heat　conduction　mode.　The　method　can　improve　the　forming　efficiency　of　the　wire　feeding　laser　additive　manufacturing,　　and　the　melting　rate　of　the　welding　wire　is　greatly　improved　by　using　the　deep　penetration　mode.　Heating　and　melting　a　workpiece　in　the　heat　conduction　mode　can　effectively　avoid　the　occurrence　of　defects　such　as　keyhole-induced　porosity.　A　system　for　the　laser　additive　manufacturing　based　on　the　keyhole　effects　is　also　discussed.