Aluminum　alloy　(AA)　2524　is　a　new　aircraft　material　with　high　damage　tolerance　and　high　strength.　Bead-on-plate　welding　of　AA2524　with　a　thickness　of　2　mm　using　a　high　power　fiber　laser　is　presented.　Solidification　cracking　susceptibility　and　microstructures　of　the　joints　for　the　original　alclad-including　surface　(OS),　oxide-film　removed　(OR)　surface　and　alclad　removed　(AR)　surface　are　investigated　by　optical　microscopy　(OM)　and　electron　microscope.　The　results　indicate　that　the　OR　and　the　AR　joints　have　the　maximum　and　minimum　solidification　cracking　susceptibility,　respectively.　Different　surface　status　joints　have　different　grain　sizes,　morphologies　and　quantities　of　eutectic,　leading　to　the　different　solidification　cracking　susceptibilities.　The　alclad　on　the　surface　of　AA2524　can　dilute　the　alloying　elements　in　joints,　reduce　the　quantity　of　eutectic　and　weaken　the　healing　effect,　thus　increasing　the　solidification　cracking　susceptibility.　The　oxide-film　on　the　surface　of　alclad　can　be　involved　in　welding　pool,　act　as　heterogeneous　nucleation　site　playing　an　important　role　in　refining　grain　size,　promote　a　discontinuous　eutectic　distribution　and　reduce　the　solidification　cracking　susceptibility.