Flight control computer is very important for flight safety, while redundant flight control system can greatly enhance flight safety. In this paper, based on the existing flight control computer hardware architecture and comprehensive comparison of various types of buses, FlexRay bus is selected for data interaction. Through statistical analysis on the upstream and downstream data in the bus, treble-redundancy flight control computer system based on FlexRay bus is designed, in which data transmission is strictly in accordance with defined time slice. Finally, Semi-physical simulations are conducted. By comparing the output attitude angles and rudder values of three groups of UAVs, the results demonstrate the reliability of FlexRay bus and also illustrate that the designed treble-redundant fault-tolerant flight control computer based on FlexRay bus technology can improve the safety and reliability of UAV.