系统安全性分析方法是目前广泛采用的飞机安全性设计方法。由于在分析中缺乏对系统整体动态特性的检查,在设计中可能存在可靠性指标分配的不合理。通过面向安全性的风险评估,能够实现系统动态特性的综合验证。提出了一种基于割集和重要度的故障树可靠性指标分配方法,以某型飞机横向电传操纵系统安全性设计为例对顶事件不可靠度指标进行分配,然后结合基于极值理论的飞行风险评估实现了部分底事件可靠性指标的修正。 System security analysis method is widely used in aircraft safety design. Due to the lack of examination of the overall dynamic characteristics of the system in the analysis, there may be unreasonable distribution of reliability indicators in the design. Through security-oriented risk assessment, comprehensive validation of system dynamics can be achieved. This paper presents a fault tree reliability index allocation method based on cut sets and importance degree. Taking the safety design of horizontal flight control system of a certain aircraft as an example, the unreliability index of the top event is assigned. Then, based on the extreme value theory Flight risk assessment to achieve the reliability of some of the bottom event indicators amended.