The effects of single-stage homogenization technology without pre-precipitation treatment and two-stage homogenization technology treatment with pre-precipitation treatment on microstructure and mechanical properties of Al-4.3Zn-1.7Mg (wt.%) alloy ingot casting and plate were investigated contrastively by optical microscopy (OM), scanning electron microcopy (SEM), transmission electron microcopy (TEM) and uniaxial tension(TS) test. The results show that the trace elements Mn, Cr and Zr recombined in the alloy after semicontinuous casting quenching are retained in the matrix in the form of solid solution,and the pre-precipitated phase particle Al₆Mn、Al₇Cr and Al₃Zr are precipitated in the process of homogenization treatment for supersaturation solid solution. The pre-precipitated phase in the matrix is big and there is uneven distribution under the conditions of 470°C×24h single-stage homogenization technology without pre-precipitation treatment. The precipitation behavior of the precipitated phase can be improved significantly in the process of homogenization by the low temperature pre-precipitation treatment. The fine pre-precipitated phase with dispersion distribution is obtained, meanwhile, non-equilibrium eutectic organization of grain boundary also can be eliminated. The best homogenization effect can be achieved for alloy ingot casting. The precipitated phase particles has good thermal stability, and it cannot be markly coarsened in the process of hot rolling and subsequent solid solution aging heat treatment. So the migration of grain boundary and dislocation movement can be inhibited significantly, and the performance of alloy plate can be improved.