A new improved differential evolution(IDE) algorithm is proposed for solving the system reliability redundancy allocation problem. The constraints handling method is improved based on the punishing function method. The new constraints handling method doesn’t need to calculate the every punishing function value in the search process, which greatly speeds up the searching for the optimized solutions. The proposed method has good generality, which can be introduced completely to other intelligent optimization algorithms. Using the improved algorithm to solve four typical system reliability redundancy allocation problems, the experimental results show that the algorithm has good optimization precision and convergence speed.