The utility model discloses a current collecting device of a ring main unit which is externally connected with a computer. The current collecting device of the ring main unit comprises a current sensor, a current-voltage switching circuit, an A/D convertor, a microprocessor and a power source. The current sensor, the current-voltage switching circuit, the A/D convertor, the microprocessor and the computer are sequentially connected. The power source is respectively connected with the current-voltage switching circuit, the A/D convertor and the microprocessor. According to the current collecting device of the ring main unit, the current-voltage switching circuit is additionally arranged and power loss borne by each resistor is reduced through the method that a plurality of resistors are connected in parallel, so that interference is reduced and accuracy is greatly improved.