Abstract: Iron and steel enterprises in China have formed a group-based development model, and the “one headquarters, multiple bases” management and control model has effectively improved enterprises ability to respond to the complex and volatile market. Aiming at the practical demands of group-based iron and steel enterprises, such as centralized sales, distributed manufacturing and low-cost delivery, a mathematical programming model for the joint optimization of order allocation and transportation mode is established, and an improved genetic algorithm is proposed for solution. The genetic algorithm adopts a two-layer coding scheme to represent the optimal decision scheme of order-base-transportation mode, and implements individual selection through a hybrid strategy combining roulette wheel selection and elitist preservation. A neighborhood search procedure is designed as the mutation operator to ensure solution feasibility while enhancing local optimization capability. Computational experimental results show that the genetic algorithm proposed in this paper can stably obtain high-quality planning schemes that meet enterprise requirements within acceptable time for large-scale cases.