Introduction  In order to meet the requirements of production monitoring and operation management of offshore converter stations， the overall design， main performance and functional requirements of the intelligent auxiliary control system for offshore converter stations is proposed.

  Method  The system was composed of electrical equipment online monitoring， ventilation and air conditioning monitoring subsystem， submarine cable monitoring subsystem， environmental monitoring subsystem， video monitoring subsystem， fire alarm subsystem， fog whistle monitoring subsystem， robot inspection subsystem， etc. It realized the linkage control between the subsystems through the auxiliary control system background， including fire fighting， HVAC， video， etc.

  Result  The functions of data collection， operation monitoring， operation control and system linkage were realized.

  Conclusion  Therefore， the solution meets the technical requirements of unattended operation and can effectively reduce the operation and maintenance costs of offshore wind farms.