Abstract: The effects of the proportion of foundry returns on the microstructure and properties of Al-Si alloy in cast and treatment states were studied.The results show that the tensile strength and yield strength of the as-cast alloy keep a small increasing trend with the increase of the proportion of foundry returns, the elongation does not change much when the proportion of returns is not more than 20%, but when the amount of returns is 30%, the slender acicular Fe phase increases, leading to a decrease in the elongation.After heat treatment, compared with no returns addition, when the proportion of the returns is 10%and 20%, the tensile performance of the alloy is not affected by the returns, when the proportion of the returns reaches 30%, it has a great influence on the elongation, and the tensile strength and the yield strength decrease by about 5%and the elongation decreases by about 55%.