The invention discloses a steering-by-wire system with a signal fault-tolerant function and a control method, and belongs to the field of automobile steering control. In the running process, through collecting the turn angle of front wheels, the yaw velocity, the lateral acceleration and the current of a steering motor, the fault condition of sensors is jointly detected and diagnosed, if one sensor fails, the fault condition is obtained through estimation compensation of signals of the rest sensors, and an automobile is controlled to steer. Through detecting and diagnosing the fault condition of the sensors in real time, signal reconstruction can be performed on line in the event of a failure, the fault signal is compensated to be input as a signal, an accurate response to the steering command of a driver is made, robust control over the steering motor is realized, and thus the reliability of the steering-by-wire system and the stability and safety when the automobile runs are improved.