Abstract: The effects of alloying element content, casting temperature and injection pressure on the microstructure of die cast aluminum alloy were studied, and the microstructure characteristics and porosity were evaluated. Sampling and microstructure observation of high pressure casting parts were carried out, and the change mechanism of their microstructure was studied. The results show that lower pressure and lower filling temperature increase the porosity of high-pressure cast Al-Si-Cu alloy, promote the formation of coarse iron-rich intermetallic compounds, and change the morphology of α-Al phase.Variation of alloying element content changes the microstructure of the part under constant casting process parameters.