This　text　does　on　research　on　welding　behavior　of　the　Ni3Al　alloy　casting　MX246A　of　based　on　laser　as　heat　source.　First　process　parameters　have　effects　on　crack　sensitive　in　the　study.　Laser　power　decided　to　heat　input　and　the　depth　of　the　weld,　which　has　obvious　effects　on　the　hot　crack.　Crack　sensitivity　of　welding　at　low　speed　is　quite　lower　than　it　at　high　scanning　speed;　low　scanning　speed　can　reduce　the　sensitivity　of　weld　cracking.　Because　of　the　laser　absorption　and　solidification　of　weld　metal　for　inheritance　of　the　basic　material,　grain　degree　of　materials　makes　a　significant　impact　on　crack.　Crack　sensitivity　in　the　fine　grain　areas　is　quite　lower　than　it　in　the　coarse　grain　areas.　It　is　found　in　the　study　that　the　main　reason　for　the　weld　crack　is　Mo　elements　gathering　and　caused　the　oxidation　of　the　partial.　Welding　of　MX246A　alloy　is　realized　on　the　basis　of　the　above　research,　and　performance　of　welding　joint　is　up　to　more　than　75%　of　base　material.