Effect of aging treatment on the microstructures and mechanical properties of 7N01 Al alloy was investigated by differential scanning calorimetry, transmission electron microscopy, microhardness measurement and tensile test. Maximum hardness(125.7Hv) and tensile strength(447.3MPa) were obtained from the specimen aged at $120^{circ}C$ for 32hrs. The major precipitation hardening phase was confirmed as coherent $MgZn_2({eta}^{prime})$ phase. Microhardness changes after peakaged condition showed very large decrease upon increased aging time. This result was attributed to the high transformation rate from coherent ${eta}^{prime}$ to incoherent ${eta}$. It was found that the precipitation sequence of 7N01 Al alloy was GP zone${ ightarrow}$metastable spherical hcp $MgZn_2({eta}^{prime}){ ightarrow}$ equilibrium rodlike hcp $MgZn_2({eta})$.