The present work was aimed to examine the variation of precipitations and mechanical properties by thermomechanical treatments (TMT) in Al-2.19 wt%Li and Al-2.0 wt%Li-0.11 wt%Zr alloys. This study was performed by TEM, SEM observation, DSC, electrical resistance measurement, hardness and tensile strength measurement. First peak of resistivity aged at $90^{circ}C$ was caused by precipitation of ${delta}^{prime}$-precursor phase, and second peak was caused by precipitation of ${delta}^{prime}$ phase. According to this result, the precipitation process of Al-2.19 wt%Li alloy was as follow : $SSSS{ ightarrow}{delta}^{prime}$-precursor phase ${ ightarrow}{delta}^{prime}$ (Coherent ${ ightarrow}$ Semi-coherent) ${ ightarrow}{delta}$. In a Al-2.0 wt%Li-0.11 wt%Zr ternary alloy, the first peak of resistivity was appeared at initial aging heat-treatment. It is result from exsistant of ${delta}^{prime}$-precursor phase. The effect acceleration in a binary alloy was not appeared and the over-aging ternary alloy was accelerated with increase of the reduction rate. It is caused by combination effect of ${delta}^{prime}$ and composite phase.