Abstract: The effect of melt ultrasonic treatment (400 W) on the pores,microstructure and as-cast component distribution of 7050 aluminium alloy was studied by metalloscopy,Archimedes’ method,scanning electron microscopy and electron probe micro analysis.Te results indicate that good degassing and refinement results could be obtained after the melt was treated by ultrasonic.As the ultrasonic treatment time was prolonged,the pores in the ingot decreased at first and then increased,while the density of the ingot increased at first and then decreased.The as-cast microstructure was refined at first and then was coarsened.When it was treated by ultrasonic for 90 s,the degassing and refinement effects were the best,a compact as-cast microstructure with no pore could be obtained.Ultrasonic treatment could also reduce the formation of second-phases at grain boundaries and make the component distribution more uniform.