Fault detection method and device for railway vehicle system

The embodiment of the invention provides a fault detection method and device for a railway vehicle system. The method is applied to the fault detection device for the railway vehicle system. The fault detection device for the railway vehicle system comprises an excitation signal sending device and an excitation signal receiving device which are connected with the two ends of a bus of the railway vehicle system correspondingly. The excitation signal sending device generates excitation signals and injects the excitation signals into the bus of the railway vehicle system in a voltage superposition mode. The excitation signal receiving device receives detection signals through the bus of the vehicle system and judges whether the detection signals meet preset fault detection conditions or not; and if yes, the excitation signal receiving device sends early warning information, the early warning information is used for indicating that the railway vehicle system has faults, the physical state of the bus is provided in time, and bus faults can be found in time.