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Aiming at the poor ductility, toughness and formability of Al-li alloy, the effect of per-pass reduction on microstructure and mechanical properties of 2197 Al-Li alloy were studied by OM/SEM microstructure analysis, tensile properties and hardness/conductivity test, with a constant total reduction of 75%. The result show that the grain structure, the amount and distribution of precipitates are significantly affected by per-pass reduction. The strength of as-rolled alloy increases significantly with the increase of per-pass reduction, while the ductility and toughness decrease obviously. After T8 aging treatment, a large amount of precipitates are produced and the PLC (Portevin-Le Chatelier phenomenon) effect in the rolled alloy is eliminated. The mechanical properties of the alloy rolled by light and heavy reduction are improved significantly. After aging treatment, alloy exhibits the optimal comprehensive mechanical properties with tensile strength of 384.94MPa and the elongation to fracture of 12.45%, which are 2%, 21% and 29%, 31% higher than those of the light and middle reduction alloys, respectively.