Abstract: The thermodynamics-dependent physics parameters and equilibrium phases precipitation of Al-(6.0-8.0) Zn-(1.8-2.8) Mg-(1.4-2.6) Cu alloys were analyzed by using software package JMat-Pro for material property simulation of Al-base alloys. The resuls show that the partial Gibbs free energy of alloy elements Zn, Mg, Cu, Fe, Si and Zr are all negative. The maximum activities of Zn, Mg and Si are 0.2, 0.061 and 0.069, respectively.The activities of Cu, Fe and Zr closes to 0. The start temperature of η, S and T phases precipitation are in the temperature range of (407-443 ℃), (405-473 ℃) and (111-176℃), respectively.The amount of η phase precipitation increases as the contents of Zn increases, whereas decreases as the content of Cu increases. The amount of S phase precipitation increases as the content of Cu increases, whereas decreases as the content of Zn increases.The amount of T phase precipitation increases as the content of Mg increases, whereas decreases as the content of Zn and Cu increases.