Roles of fundamental and additional hardening precipitates on the changes of mechanical properties and electrical resistivity during precipitation decomposition in binary Al-Li, ternaty Al-Lieu and multi-Li-Cu-Mg-Zr alloys have been investigated by the detailed measurement of electrical resistivity, hardness and tensile strength and the observation of transmission electron micrographs. Peek hardness and tensile strength in multi-component Al-Lieu-Mg-Zr Alloy had higher than that of the other alloys and the results of measurement of hardness, strength and electrical resistivity in each alloys aged at 90 and 190℃ precipitation behaviors and mechanical properties in binary, ternary and multi component Al-Li alloys were contributed to the δ`, precursory phase of δ`, T₁, G.P.B. zone and S`phases, respectively.