On the basis of our previous work, differential evolution with grey-mean-best mutation (DE/GmBest/1), this study attempts to apply it to identify an unknown system whose structure is assumed to be known in advance. The search performance of DE/GmBest/1 is compared with two standard DEs, DE/rand/1 and DE/best/1, and our previous work, DE with mean-best mutation strategy (DE/mBest/1) in terms of parameter accuracy, convergence speed and reliability. Simulation results demonstrate the effectiveness of DE/GmBest/1 algorithm. The results also show that grey-mean-best mutation strategy performs better than mean-best mutation strategy.