High-performance die-casting aluminum alloy for automotive body and preparation method thereof

The invention relates to a die-casting aluminum alloy for an automotive body and a preparation method of the die-casting aluminum alloy. The die-casting aluminum alloy comprises the following raw materials in percentage by weight: 9.5-11.5 percent of Si, 0.3-0.6 percent of Mn, 0.1-0.6 percent of Mg, 0.1-0.2 percent of Ti, 0.01-0.02 percent of Sr, 0.02-0.04 percent of B, less than 0.25 percent of Fe and the balance of Al. The preparation method comprises the following steps of: mixing the raw materials in a resistance crucible furnace; and adding Ti, B and Sr into an aluminum alloy melt in a form of intermediate alloys of Al-5Ti-B and Al-10Sr during smelting to prevent burning loss of Ti, B and Sr, wherein the tensile strength of the prepared die-casting aluminum alloy at a casting state is more than 225MPa and the elongation is more than 6 percent under a rapid shot process condition that the casting temperature is at 680 DEG C and the speed is 4.0m/s. The die-casting aluminum alloy is high in flowability, and suitable for mold filling of large thin-walled workpieces; and a die-casting piece at the casting state is high in ductility and tensile strength and can meet the requirement of a structural part of the automotive body.