Homogenization treatment for Al-Zn-Mg-Cu alloy with Ho addition was investigated by scanning electron microscope (SEM), optical microscope (OM), and differential scanning calorimeter (DSC). Electrical conductivity and micro-hardness were tested during different homogenization processes. The results show that there are four kinds of second phases in as-cast alloy: T(AlZnMgCu), Al₇Cu₂Fe, Al₈Cu₄Ho and S (Al₂CuMg), which cause severe micro-segregation in microstructure. After homogenization treatment at 475 °C for 20 h, T phase is completely dissolved back into matrix and no S phase is observed, with Al₇Cu₂Fe and Al₈Cu₄Ho remaining. Micro-hardness and electrical conductivity are associated with vibration of T phase, dissolution of which can increase micro-hardness and decrease electrical conductivity. Besides, precipitation of Al₃Ho also contributes to the increase in both micro-hardness and electrical conductivity during homogenization at 475 °C for 5~20 h. Finally, through homogenization kinetic analysis, the appropriate homogenization parameter is determined as 470~475 °C/20~25 h.