中文摘要：

利用条件概率评价及系统工程理论，将关键块体作为块体系统一个重要组成部分，分析了关键块体可靠度指标评价办法，探讨了关键块体与次生关键块可靠度内在关系，由此类推，提出块体系统评价方法，推导出块体系统可靠度计算公式，实现对块体系统的失稳概率的评价计算。并选择一工程实例，对评价方法予以验证。结果表明：传统关键块体可靠度评价办法忽略块体间内在影响，结果偏向风险；而文中方法综合考虑块体之间影响，并建立了系统评价模型，对块体系统评价更接近实际情况，对块体系统理论的研究有一定借鉴意义。

英文摘要：

Based on conditional probability evaluation method and systematic engineering theory, considering key block as the important part of blocks system, the evaluation method of reliability of key block was analyzed, then we discussed the inner-relationship between key block and secondary key block, and following the same thought, we knew the relationship between secondary key block and the following block easily, so it would be possible to establish the systematic blocks evaluation model if we had gotten the reliability result of each block. With the reliability evaluation formula of Series System, we could calculate the reliability of systematic block. The suggested method was applied to a hydropower project in Southwest China so as to test its reasonableness. The results demonstrated that it was more coincidence to practical situation of the engineering than traditional evaluation of key-block theory. It would have some extent reference for the research of systematic blocks theory.