The invention discloses a method and a device for processing the signal fault of a dual-speed sensor of a gas turbine. The method comprises the following steps: processing a sensor signal and a faultdiagnosis parameter by a fault diagnosis module to obtain a sensor state signal; processing a sensor signal, a signal processing parameter and the sensor state signal by a signal processing module toobtain a sensor selected value and a sensor difference value signal; and processing a sensor difference signal, the sensor state signal and a alarm timing parameter by an alarm timing module to obtainan alarm signal. According to the method, preliminary trouble shooting can be carried out on the sensor signal, the sensor which is of obviously a hard fault is excluded from a calculation range, andthe calculated rotating speed value is ensured not to deviate too much.