Abstract: A subsea oil field located in South China Sea was developed in 2012. Its power supply and control system is via a 14 km subsea umbilical from a floating production platform which is about 12 km away. Electro-hydraulic multiplex control system is adopted to control a total of 8 subsea wells. The oil field subjected to an early pre-mature failure to its control system due to insulation resistance problems of the subsea umbilical’s electrical quads. An innovative design was conducted to use the oil field’s spare medium voltage ESP power cable triad in replace of the failed umbilical quads in order to restore the remote control. After research and analysis, special subsea splicing apparatus was designed and implemented to transit the three medium voltage cores flying lead to two low voltage flying leads which connect to the original subsea well head control system. A two channel with 100% redundant control requirement was achieved through the novel design. The innovative engineering and successful application of the splicing apparatus restored the remote operation control of subsea oil field, and the system has been operating steadily for many years.