Pulsed　laser　welding　was　used　to　join　ultra　thin　Inconel　718　alloy　foils　whose　thickness　was　0.2　mm.　A　fixture　was　designed　to　obtain　the　edge　joint.　The　joint　geometry　and　hot　cracking　were　both　observed　on　the　cross　sections.　The　relationship　between　the　height,　width　of　the　joint　and　the　energy　density　were　fitted　as　linear　functions.　The　effect　of　heat　input　on　the　hot　cracking　in　the　edge　joint　was　obtained.　It　was　shown　that　a　hot　cracking　occurred　during　the　solidification　of　the　molten　metal　under　laser　heating.　The　crack　initiated　at　the　gap　between　the　foil　pair　and　propagated　along　the　Laves　phase　with　low　melting　point.　The　crack　length　could　be　reduced　by　applying　low　heat　input.　Tearing　tests　were　conducted　to　evaluate　the　influence　of　the　cracking　on　the　mechanical　performance　of　edge　joints.　There　existed　two　failure　modes　for　the　edge　joint　under　a　tear　loading.　When　the　crack　length　exceeds　106.9　μm　the　hot　crack　starts　to　propagate　and　the　tear　loading　decreases　with　crack　length　increasing.　A　finite　element　model　was　established　to　simulate　the　stress　evolution　during　the　cooling　stage.　The　main　reason　of　crack　initiation　and　propagation　were　both　presented.　©　2021　The　Society　of　Manufacturing　Engineers