Al-Zn-Mg aluminum alloy medium-thick plate and preparation method thereof

The invention belongs to the technical fields of metal materials and processing thereof and discloses an Al-Zn-Mg aluminum alloy medium-thick plate and a preparation method thereof. The aluminum alloy medium-thick plate mainly comprises the following element components: 1.0-2.0 of Mg, 6.0-7.0 of Zn, less than or equal to 0.05 of Cu, less than or equal to 0.08 of Fe, less than or equal to 0.05 of Si, less than or equal to 0.05 of Cr, and the balance of Al and inevitable elements, wherein each inevitable element is less than 0.05 and the total amount of the inevitable elements is less than 0.15. The Al-Zn-Mg aluminum alloy medium-thick plate is prepared by adopting a hot rolling method, and the prepared aluminum alloy medium-thick plate has the thickness of 5-10mm and the surface hardness more than or equal to 150HV; meanwhile, plate surface is uniform, no blank mark is formed, and colour is uniform and close to natural colour of pure aluminum metal after anodic oxidation, so that the Al-Zn-Mg aluminum alloy me