This invention involves an automobile lamp device and a method for emitting signals through light thereof. This invention divides the network communication protocol for the communication between automobile into a software protocol layer (L1), a signal protocol layer and a physical protocol layer wherein the software protocol layer is used for checking coding and decoding the data required to be sent and received by a system, and the signal protocol layer is used for performing combined coding of data package signals and basic light signal on data packages produced by the software protocol layer according to the protocol agreement, and the physical protocol layer is used for converting digital signals and light signals mutually. The device comprises a light receiving apparatus arranged at the head of the automobile and a light emitting device arranged at the tail of the automobile. The light emitting apparatus collects the operating status information of automobile, performs information exchange with surrounding automobiles through digital information. The device solves problems that in the prior art, lamps cannot be served as communication mediums to realize communication and positioning among automobiles.