The invention relates to a technology method for reducing anisotropism of an Al-Mg-Si alloy plate, and belongs to the technical field of aluminum alloy machining forming. The solid dissolving and double-level overageing thermal processing technology is added between traditional hot rolling-cold rolling technologies, the needed thickness of a finished product is achieved through cold rolling, and finally short-time solid dissolving, quenching and preageing processing are carried out; precipitated phase particles generated through overageing are utilized for changing the cold rolling deformed structure, accordingly, the recrystallized structure of the alloy following technology process is affected, and the purpose of improving the final anisotropism of the Al-Mg-Si alloy plate is achieved. According to the technology method, the solid dissolving and overageing processing technology only needs to be added between hot rolling and cold rolling at a time, the plane anisotropism of the finished plate can be reduced, and the mechanical performance and the punching forming performance of the plate are not affected. The technology is simple, control is easy, operability is high, the technology is economical and practical, and the technology method can be applied to the production of the Al-Mg-Si system alloy plate.