Abstract: TCB is the collectivity of the computer’s protector，which influences the security of system.With the development of the information technology，the boundary of TCB has been expanded.The validity of the TCB expanding becomes more and more important for information security.At present most of the researches of TCB are focused on the technology of trusted chain，and there is almost no theory research.This paper puts forward Trusted Expand Model of TCB（TEMT） based on the idea of trusted computing，in which TCB is divided into several TCB subsets.The trusted support relation between TCB subsets is formally described，and an important theorem is proved.At last an implement framework is proposed.

Key words: trusted computing, Trusted Computing Base（TCB）, Trusted Computing Base（TCB） subset

摘要： TCB的可信性与系统安全密切相关。随着TCB边界的不断扩大，保证TCB边界可信扩展成为信息安全防范的重要环节。目前针对TCB扩展的研究主要集中在技术层面，理论研究相对欠缺。基于可信计算思想研究了TCB可信扩展模型，依据安全策略将TCB层次化分割为TCB子集，形式化描述了TCB子集之间的可信支撑关系，证明了TCB可信扩展性的必要条件，提出了模型的实施框架。

关键词: 可信计算, 可信计算基（TCB）, 可信计算基（TCB）子集