Light aluminum alloy pipe

The invention discloses a light aluminum alloy pipe which comprises an aluminum alloy outer layer and a plastic inner layer. The aluminum alloy outer layer and the plastic inner layer are combined together through prestressing force and manufactured into the aluminum alloy pipe through a seamless extrusion forming process. The aluminum alloy outer layer is made of light aluminum-magnesium alloy material which comprises, by mass, 5% to 10% of magnesium, 0.5% to 1% of copper, 0.2 % to 0.8% of nickel, 0.2% to 0.5% of manganese, 0.1% to 0.5% of iron, 0.4% to 0.8% of chromium and the balance aluminum and inevitable impurities. The plastic inner layer is made of thermoplastic PP-R plastic. In this way, the dual-layer combination structure is adopted, and the aluminum alloy pipe is formed by combining the aluminum alloy outer layer and the thermoplastic plastic inner layer through prestressing force, has the advantages of being resistant to corrosion, high in rigidity and strength and resistant to impact, and meanwhile has the advantages of being light in weight, easy to prepare and low in cost.