Abstract: This paper proposes a fault-tolerant architecture for application in the steer-by-wire system. The architecture involves the ECU redundancy, motor redundancy, bus transmission channel redundancy, sensor redundancy, software redundancy. By employing the Markov model of the sensor with triple-modular redundancy, we determined the relationship between the reliability, the failure rate and the fault detection coverage. Then, we used the failure mode and effects analysis (FMEA) method to list all kinds of system failures to form system-level FMEA tables, which have been used to establish the Markov model of the whole system. Through the solution of Markov differential equations, we obtained the reliability of the whole system R(t). Compared with the non-redundant steer-by-wire system, our results showed that the reliability of the new system is always high in the life of the vehicle.