The invention provides a preparing method for a 700-MPa-
level aluminum alloy extruded section. The 700-MPa-
level aluminum alloy extruded section is prepared from, by weight percentage, 7.8% to 10.3% of Zn, 1.3% to 2.0% of Mg, 1.3% to 2.0% of Cu, 0.08% to 0.15% of Zr, smaller than or equal to 0.15% of Si, smaller than or equal to 0.15% of Fe, smaller than or equal to 0.15% of other impurities and the balance Al, wherein the weight percentage of each kind of the impurities is smaller than or equal to 0.05%. The preparing method includes the steps that the raw materials are prepared according to
alloy components, fused, subjected to furnace refining and standing, and then cast into an alloy
ingot with the required specification; and the alloy
ingot is subjected to preferred three-stage homogenizing, then formed through a preferred
extrusion technology and can be used for part
machining after heat treatment. The novel aluminum alloy extruded section is even in microscopic structure and stable in performance, and the
ultimate tensile strength can be higher than 700 MPa; and meanwhile elongation is higher than 8%,
fracture toughness is higher than 26 MPa.m<1 / 2>, the current
aerospace material selecting requirement is met, and meanwhile the aluminum alloy extruded section can be widely applied to the fields of the
nuclear industry, transportation, weapons and the like.