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 surface (OR) 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.