Abstract: To solve contradictions between market demands and productivity,the problem how to arrange the production,which not only meets the needs of many customers for all types of products,but also gives full play to productivity was discussed under the premise of smooth running in iron and steel plants.A domestic special steel plant, which produces long products,was chosen as an example,and the reasonable proportion of different type of products was analyzed in combination with the concepts of product structure and productivity.The relationship between product structure and productivity was studied from three aspects of the equipment,the processes and the steelmaking plant. Finally,a method was proposed to calculate the reasonable product structure and productivity.