Abstract: 1420Al-Li/Mg-9Li/1420Al-Li composite plate with high-strength, corrosion-resistant and ultralight 1420 Al-Li alloy as the cladding plate was successfully prepared by one-pass hot rolling. The interfacial microstructure and mechanical properties of the composite plates by hot rolling at 450 ℃with different reductions were investigated. The results show that when rolling pressure is 35%, the composite plate is only partially bonded-mechanical bonding+metallurgical bonding and no compounds are formed at the interface, the tensile strength of the composite plate is 236 MPa, elongation is 26%. As the rolling pressure is 50%, the composite plate can be formed by metallurgical bonding and unbounded compound. The tensile strength of the composite plate is as high as 272 MPa, and the elongation is 14%. While improving the corrosion resistance, the strength of the Mg-9Li alloy is greatly improved.