Abstract: Analyzes the traditional CAD systems,this paper has introduced a concept of design Knowledge Units（KU）,which includes conceptual information.Based of KU,the design rules are expressed by BNF.Using these knowledge and rules,a way to design products structure has then been developed.A Hot-Runner multi-cave mold system has been realized by this way.

摘要： 分析了产品设计现状,采用了知识单元概念,将概念信息封装于知识（结构）单元;基于知识单元对设计规则进行BNF表示,提取产品设计知识与规则;提出了基于概念信息知识单元的产品结构设计方法;该方法在多腔模系统设计中得到了成功应用。