The work aims to study in-flight particles, splat particles and coating structure produced during arc spraying of AlMg/Al2O3 cored wires, as well as impact resistance of the coatings. Two kinds of Al-base cored wires containing micron-grade Al2O3 particles were developed. The collected in-flight particles and splats particles produced during arc spraying, as well as coating microstructure were characterized with SEM. Impact resistance of the coatings was tested with a self-made apparatus. Three different types of in-flight particle, namely, AlMg, AlMg clad Al2O3, Al2O3, were generated during arc spraying of AlMg/Al2O3 cored wires. With the decrease of Al2O3 particle size, the AlMg clad Al2O3 particles consisted of thicker AlMg film and more Al2O3 particles. The splat shapes were irregular and complex, and the surfaces were uneven and subject to sputtering. The coating structure was compact and less defective. When the particle size range of Al2O3 particles was 400~500 μm, the average area content of Al2O3 particles on the surface of AlMg/Al2O3 coating was 5.52%, but it was 13.54% When the particle size range is 30~50 μm. Indicating that more Al2O3 particles accumulated in the coating containing Al2O3 particles of small particle size. Under the effects of 500 cycle cyclic impact tests, the AlMg coating and AlMg/Al2O3 coating exhibited no obvious radial, circular cracks and large area flaking, but obvious plastic deformation existed. The content of Al2O3 particles increases as the particle size of Al2O3 particles decreases. The as-prepared AlMg/Al2O3 coating absorbs most of the impact work through plastic deformation, reduces possibility of impact fa-tigue crack generation, and maintains a good bonding between coating and substrate.