Abstract: For nine different redundancy configurations of flight control system, the simplified estimatione formulas of system loss probability are introduced.From these formulas the effects of redundancy configuration and its management made on the system reliablity are analysed and compared.Results obtained from both mathematical and physical aspects are as follows:（1）With the state of theart of manufacturing, the pure triplex configuration with self monitoring does not satisfy the high reliability requirement, if thereis no enhancing redundancy for independent part（computer）.（2）The integrated triplex/quadruplex configurtion has some ideal performances of the reliability, maintainability, cost-efficiency,and single failure rate. If the independent part is quadruplex while the other dependent parts （sensors, actuators, and I/O interface, etc.）are triplex, the cross loss probability（which occurs by introducing ineffective dependent part due to the failure of independent part）will decrease to a unimportant level of amount.Under this condition, the use of autonomous I/O device and/or direct hard wire interface between sensors and computers, as well as actuators and computers, has no significant effect.（3）The sensors redundancy reconfigurable strategy added, to previous integrated system futher increase the reliability of the integrated system,and its sensitivity to the monitoring coverage is the lowest in the nine configurations.Therefore, for the application to future systems of which the reliability reqirements are more higher than that of present systems, this system will be the preferred configuration.