The main objective of the utility model lies in providing a direct-current system and a control device thereof. The control device comprises a switch which is disposed in a locking loop of the direct-current system; and an electric control mechanism which is disposed in the direct-current system and used for controlling the switch. Through the system and device which are provided by the utility model, a problem that the manual operation of a knife switch in the prior art is liable to cause the misoperation of the direct-current system is solved, and the operation automation of the knife switch of the direct-current system is achieved, thereby achieving an effect that the direct-current operates safely and stably.