The offshore drilling DC drive system includes drilling package drive and marine drive, which can use ROSHILL analog DC control system or SIMENS digital DC control system. Each set of DC drive system includes thyristor rectifier bridge, surge suppression circuit, contactor control circuit, DC control components, cooling fan and other devices. The above devices are installed in a drive cabinet (SCR cabinet), which is installed in the electric control room. It can be equipped with three, four or five cabinets according to the needs of the rig. It has the characteristics of easy operation, high reliability, superior performance and easy maintenance.