Differential Evolution (DE) is a novel evolutionary computation technique, which has attracted much attention and wide applications for its simple concept, easy implementation and quick convergence. In order to tackle much overhead, problem-dependent parameters, etc and enhance the precision of classical DE, an Improved DE(IDE) algorithm is proposed by using an dynamical mutation operator adjusting the step size based on search space with evolution. Experiments of solving well-known benchmark functions in MATLAB show the improved approach outperforms existing algorithms, and dynamic mutation is a effective improvement ideas.