中文摘要：

为了建立完善的机械对称性概念体系,系统地研究机械对称性、提炼机械对称性设计准则以及指导对称性在机械设计中的科学应用,在大量研究机械对称性实例的基础上,对已有机械对称性概念体系进行改进和完善,提出按结构对称性、原理对称性和功能对称性分类的机械对称性的概念和层次结构体系.给出各种对称性的定义,举例说明了它们在机械中的存在和作用原理.探讨结构对称性、原理对称性及功能对称性在改进和创新产品中的应用方法.举例分析表明：所提出的概念体系完整的体现了对称性在机械系统中的各种存在,为进一步研究机械对称性设计规律,建立机械对称性设计方法提供了理论基础.

英文摘要：

On the basis of the research on a large number of instances concerning mechanical symmetry,the existing concept system of mechanical symmetry was improved and completed,and the concept and hierarchical system of mechanical symmetry classified by structure symmetry,principle symmetry and function symmetry was presented to support establishing a comprehensive mechanical symmetry concept system,systematically researching mechanical symmetry,refining design principles of mechanical symmetry,and directing applications of symmetry in mechanical design.The definitions of all kinds of symmetries were provided,and their existence and working principles in mechanical systems were illustrated by accurate instances.The application strategies of structure symmetry,principle symmetry and function symmetry on improvement and innovation of products were also illustrated.Analysis of instances showed that the concept system could completely contain all kinds of existence of symmetry in mechanical system,and it offered theoretic foundation for further research on mechanical symmetry design principles and the development of mechanical symmetry design methods.