In order to meet the development needs of aero-engine with high precision， high strength and light weight， this paper is based on the existing aluminum alloy investment casting technology， to carry out Sr modification treatment and blast cooling process cross-application comparative test in the process of melting and pouring. The microstructure of the samples under different conditions is observed by optical microscope， and the samples under different conditions are tested by tensile machine， so as to study the influence of Sr modification treatment and blast cooling process on the microstructure and properties of the Al-Si-Cu alloy. The results show that when using Al-10Sr intermediate alloy as a grain refiner and blowing cooling in the Al-Si-Cu alloy investment casting process， the most obvious refinement and dulling effects on the α-Al grains and eutectic Si phases in the alloy microstructure occur， and the highest mechanical property indicators are achieved. The average tensile strength， the average yield strength， and the average elongation reach 313 MPa， 246 MPa ，and 6.9%，respectively.