Product innovation as the main driving force for the development of enterprises, the degree of user satisfaction directly determines the competitiveness of products and enterprises in the industry, and with the rapid development of information technology, the proportion of user participation in product design is also gradually increasing. To address the lack of user participation and the lack of support methods for the whole process of iterative design, this paper proposes a multi-level iterative design method based on demand-solution interaction, which realizes the continuous information feedback between users and designers through the constant interaction of the generation of design requirements and solutions, and eliminates the design bias in each iteration, to make the demand and solution continuous cycle of iterative improvement, and ultimately obtain a design solution that meets the users’ needs and finally get a design solution that meets user needs and solves design problems. A case study of actual polymerization reactor production is introduced to design a horizontal inner jacketed polymerization kettle by the proposed design method, which realizes uniform and efficient cooling of the polymerization reactor during the production operation, thus improving the working efficiency and energy utilization efficiency of the polymerization reactor.