Abstract:The effect of Mn and Zr on the microstructures and properties of new type Al-Mg-Si-Cu alloys were studied, the type and composition of the precipitates were analyzed by XRD, EDAX and TEM. The results showed that the strength decreased and ductility increased with adding Zr. Adding both 0.03%Mn and 0.08%Zr, granular or rod AlCrMnFeSi dispersoids were present profusely in the microstructures of the alloy-T6, both the strength and ductility of the alloy increased. Continuously increasing Mn and Zr, the properties decreased due to the reduce of precipitate-strengthening phase Mg2Si and the occurrence of coarse AlCrMnFeSi.