Abstract: The product data model of structural design is rarely studied，therefore a gap is formed in whole product data models．After analysing the product data models in lead＿ time and the character of structural design，the product data model of structural design is researched．This paper presents the concept of structure basic element，structure variable element and the structure variable element design method．Based on the structural variables，a product structural data model is established and implemented with a list of class chain．