Disclosed are an optical multiplexing and demultiplexing module having an automatic discovery function, comprising a signal transmission portion and a signal reception portion. The signal transmission portion transmits information about the optical multiplexing and demultiplexing module by modulating transmission power of a laser. The signal reception portion samples and decodes the received optical power signal to acquire information about the other optical multiplexing and demultiplexing modules borne thereon. In configuring a wavelength division multiplexing transmission system, the device of the present disclosure may simplify the complexity of manual configuration, improve the accuracy of configuration, reduce the cost and failure rate in a solution in which an individual transceiver is used as an automatic discovery function, and adapt to different connection modes. Thereby at a receiving terminal, a signal can not only be received by a demultiplexing input terminal but also be received by various multiplexing input terminals.