The invention discloses a method and a system for enabling a redundant system to be accessed to a single-path bus, which realize the target of enabling the redundant system to be accessed to the single-path bus with a unique device address. According to the technical scheme, the system comprises a main device and at least one standby device, wherein the main device and all standby devices are equipped with the same bus address and all comprise processing modules, communication modules and switching modules; the processing modules, the communication modules and the switching modules are serially connected in sequence; and the switching circuit is serially connected onto an external single-path bus interface. When the main device is normal, the switching circuit in the main device is closed and the switching circuits of all standby devices are closed; and when the main device fails, connection with the single-path bus is actively cut off through the switching circuit, and after one standby device detects the main device fails, the working state of the main device is switched automatically through closing of the switching circuit.