By using a novel surface modification technique named ultrasonic-electropulsing coupling rolling (UECR) process on an A1-Si casting alloy rod,the surface of material was smoothened significantly.Meanwhile,a strengthened layer with a gradient change in hardness was obtained in the outer surface,corresponding to a homogeneous gradient nano-/microstructure.The thickness of nanometer-thick laminated structures was at least 40 μm,which was much thicker than conventional ultrasonic rolling process.During UECR,the formation of the well-defined nanocrystalline structure was attributed to the high strain rate and simultaneous annealing process realized by ultrasonic impact and electropulsing treatment.