25G OTU board is a service access module for optical fiber links. It can realize the service transmission of any rate protocol from 1.25Gbit/s ~ 25.78Gbit/s, and can be converted into CWDM or DWDM standard wavelength optical signal. It can be used in optical communication systems such as SDH/POS/SONET/SAN/ETHERNET with CWDM or DWDM multiplexer/demultiplexer to realize wavelength division multiplexing transmission. It provides a high-quality solution for solving transmission lines with insufficient fiber resources and high fiber line loss.