Abstract: The effects of aging temperature (400-550 ℃) and aging time(0-8 h) on electrical conductivity of Cu-Ni-Si-Zn-Mg alloy were analyzed. The relationship between electrical conductivity and precipitation rate of new phases was deduced, the phase transformation kinetics equation and electrical conductivity equation for tested alloy aging from 400 ℃ to 550 ℃ were determined according to Avrami phase transformation kinetics empirical formula, and the phase transformation beginning time and ending time for the alloy aging at different temperature were calculated on basis of the former achievements. The results show that electrical conductivity raised sharply in the beginning aging time, and then began to flatten. In addition, the higher aging temperature, the greater electrical conductivity when aging for the same time. The phase transformation process could be reflected by the change of electrical conductivity because of linear relationship between electrical conductivity and precipitation rate of new phases. It can be seen that the results obtained by the electrical conductivity equation are in good coincidence with the experimental results. The phase transformation beginning time and ending time for tested alloy aged at 500 ℃ were the shortest, and they were 0.34, 7 083.23 s, respectively.