The invention discloses high-strength and high-toughness Al-Mg-Si series aluminum alloy and a preparation method thereof. The high-strength and high-toughness Al-Mg-Si series aluminum alloy is prepared from, by mass, 0.6%-0.9% of Mg, 0.4%-0.6% of Si, 0.3%-0.5% of Li, 0.005%-0.015% of Zr, 0.001%-0.003% of B, 0.01%-0.03% of Re, smaller than or equal to 0.15% of Fe, smaller than or equal to 0.1% of Mn and the balance Al and unavoidable impurities, wherein the content of a single impurity is smaller than or equal to 0.05%, and the total content of the impurities is smaller than or equal to 0.15%. The Al-Mg-Si series aluminum alloy has the advantages of being high in strength, good in plasticity, resistant to corrosion and excellent in welding property and oxidizing and coloring property, is suitable for manufacturing lightweight aluminum alloy plates, pipes, bars and sectional bars for transportation means such as automobiles, ships and railway vehicles and shells of portable electronic products such as tablet personal computers, notebook computers and smartphones and has a wide market application prospect.