The invention provides a train compartment signal transmission method and device. The train compartment signal transmission method comprises the following steps: S1, receiving a first signal sent through a bridge-crossing line, and extracting first data carried in the first signal; S2, receiving a wirelessly second signal which is wirelessly sent and corresponds to the first signal, and extracting second data carried in the second signal; S3, judging whether the first data and the second data are the same or not, if the first data and the second data are the same, outputting the first signal, and otherwise, outputting the second signal. Through the train compartment signal transmission method and device provided by the invention, the reliability of train compartment signal transmission is improved.