[Purpose/significance] This paper aims to serve the decision-making of solutions to problems in the product design process, meet the demand of knowledge retrieval and reuse, and guarantee the sustainable development of products. [Method/process] Based on the double-cycle model of knowledge crystallization, it found that there are problems in the existing IBIS (issue-based Information System) model and its improvement model. Therefore, the knowledge crystallization double cycle model was used to connect the discussion dialogue model and the product design process, to construct the ‘IBIS representation supporting the product double cycle model’. In the original discussion dialogue model, ‘take the large or fetch small operators’ was used in fuzzy comprehensive decision making. However, because of this operator, some useful elements will be invalid, so ‘take the large or fetch small operators’ was replaced by the Einstain operator. [Results/conclusions] The Einstain operator draws on the idea of ​​‘take the large or fetch small operators’ to ignore the useless value data, and highly reducts the data at both ends. The IBIS representation supporting the product double cycle model has made the product design process decision service modeling based on the knowledge crystallization double cycle theory has a basic model framework, and the improved discussion dialogue model makes the core algorithm reliable.