Abstract: According to integrated management concept, the problems of matching orders and inventory and making production plan under mixed production mode on MTO and MTS in iron and steel enterprises are simultaneously considered. An optimizing model with combined objectives-minimizing the total cost of infringing contracts, preparing production and matching inventory-is proposed. Based on the characteristics of the problems, the GA with heuristic repaired strategy is designed. The instance simulation demonstrates the feasibility and effectiveness of the model and the algorithm.