Abstract: The effect of ultrasonic treatment on solidification microstructure and degassing of Al-2Sn alloy was studied, The effect of gas removal is characterized by the density method.The results show that the ultrasonic treatment has an excellent effect on refining and degassing of solidification structure of the ingot.The grain refinement effect is best when treated with 2000 W ultrasonic power for 30 s, and the microstructure of the ingot section is equiaxed grain.Ingots treated with 2000 W ultrasonic for 60 s has the best degassing effect, and the density and degassing rate of the ingot are the highest at this time, which are 2.7224 g/cm³ and 67%, respectively.Finally, the refinement and degassing mechanism of high-intensity ultrasound was also analyzed.