Abstract: The effects of mechanical vibration on the microstructure and mechanical properties of Al Si6Cu3 alloy during casting were studied. The mechanical vibration amplitudes were 5 μm, 10 μm, 15 μm and 20 μm, and the constant vibration frequency was 1000 Hz. The results obtained under vibration conditions were compared with those obtained under static conditions. The microstructure, mechanical properties and fracture scanning electron microscopy images of the samples prepared under different solidification conditions were compared. The comprehensive properties of Al Si6Cu3 alloy samples were studied. The results show that different amplitudes of mechanical vibration make Al Si6Cu3 alloy obtain different degree of grain refinement. With the addition of mechanical vibration, the micro-hardness of the casting is increased, and the tensile strength, yield strength and elongation of the alloy are all increased. In all the different mechanical vibration amplitude test conditions, 1000 Hz and 5 μm vibration conditions provide the best improvement results. The tensile fracture of Al Si6Cu3alloy is a mixture of dimple and cleavage.