Al-5.8Mg-0.4Mn-0.25Sc-0.1Zr （mass fraction, %） alloys were prepared by water chilling copper mould ingot metallurgy processing which was protected by active flux. The recrystallization temperature and nucleation mechanism of the alloy were studied by means of hardness tests, observations of optical microscopy and transmission electron microscopy. The results show that the anti-crystallization ability can be significantly improved by adding minor Sc and Zr into Al-Mg-Mn alloy. This can be proved by a much higher recrystalliztion temperature （450 ~C） than Al-Mg-Mn alloy without Sc and Zr （150 ℃）. The main reason of the great increase of recrystallization temperature can be attributed to the strong pinning effect of highly disperseded Al3（Sc,Zr） particles on dislocations and sub-grain boundaries. The recrystallizing process reveals itself the nucleation mechanism of the alloy involving not only the sub-grain coalescence but also the sub-grain growth.
