A high-quality flight control system is an important guarantee for modern high-performance aircraft to achieve safe flight and complete complex flight tasks, which is an indispensable and important link in modern aircraft design. The failure rate of single-redundancy flight control system can’t meet the requirement of safety index, and its safety is guaranteed through system redundancy design. Based on the numerical derivation of safety theory, this paper focuses on the three redundancy and four redundancies fly-by-wire control system architectures. Through quantitative calculation, the influencing factors and design principles of flight control system architecture design, such as system architecture redundancy design, CCDL architecture design, self-monitoring architecture design, and backup architecture design, are obtained to guide engineer in designing new aircraft.