The underwater environment monitoring system (UEMS) has been applied on the demonstration project of the offshore wind farm in Taiwan. The system integrates with an underwater junction box, conductivity-temperature-depth (CTD), acoustic Doppler current profiler (ADCP) and underwater sound level meter sensor to collect the data of sea currents, sea surface waves, sea levels, temperatures, salinity and underwater noise. And the UEMS is able to transmit measured data and power through subsea armored cable between junction box and offshore station.