The invention discloses a decoding device and a decoding method used for an intermittent balise of CTCS, which aim at solving the technical problem of simplifying the structure of the decoding device and improving the fault-tolerant capability of the decoding operation. The decoding device comprises a bit synchronization unit, a data segmentation unit, a data buffering unit and a decoding processing unit which are connected in sequence. The decoding method comprises the following steps: the bit synchronization unit extracts data synchronizing clock signals and serially outputs the signals to the data segmentation unit; the data segmentation unit implements logical conversion on the signals in a way of serial input and parallel output, and the output signals are stored in the data buffering unit; and the decoding processing unit implements verification decoding on the data and outputs the data to a communication device. Compared with the prior art, the decoding device and the decoding method which are applied to the information transmission module of the intermittent balise of CTCS are combined with the hardware logic design and the software algorithm optimization design, and have simple structure, stability, reliability and real-time; and the decoding device applied to the intermittent balise of CTCS has the decoding time consumption being smaller than 1ms on the average.