By means of metallography analysis and micro-hardness measurement , the microstructures and micro-hardness values of ZK60 magnesium alloy , annealed at different temperatures for different times, were compared. The effect of annealing temperature and time on structure transformation and composition homogenization was analyzed. The results showed that the annealing temperature played a main role in homogenizing of ZK60 alloy. The optimized annealing process of ZK60 magnesium alloy, that is 470°C × 14 h, was suggested.