The present invention discloses a partial power off control system of a distribution network and a distribution network system. According to the partial power off control system of the distribution network, column smart switches are installed on each outgoing line of a power system, a main transformer of the power system is grounded through an arc suppression coil, and the column smart switches can determine single-phase grounding faults. The column smart switches for determining single-phase grounding faults are installed on each outgoing line in a distribution manner, when the line has faults, the line sending the faults can be cut off intelligently, fault information and specific positions of the faults are sent to a main station and a preset smart terminal of an operation and maintenance person through short messages, so that the single-phase grounding faults are determined accurately, and the power can be provided for users in mountains more reliably.