It has been well known that physical property such as heat resistance and electric conductivity of Al-Zr alloys are closely related with precipitation behavior of Al₃Zr phase. In the present work, the effects of misch metal(Mm) addition on the precipitation process and mechanical property in Al-Zr alloys were studied. The results showed that accelerated ageing at low temperature(623K) and smaller sized Al₃Zr phases in comparison with Mm-free alloy were observed by the Mm addition, resulting in hardness increase. From the DVRC analysis indicated that the precipitation of Al₃Zr phase at low temperature(T $lt; 623K) is promoted by Mm addition. It was attributed to the heterogeneous precipitation of Al₃Zr phase at low temperature.