The utility model provides an auxiliary device for measuring the capacitance current of a power distribution network under an electrified condition. The auxiliary device comprises a PT handcart module. The auxiliary device also comprises a single-phase alternating-current contactor K; one end of the single-phase alternating-current contactor K is connected with one end of a high-impedance harmonic wave eliminator at the neutral point of the PT handcart module; and the other end of the single-phase alternating-current contactor K is connected with the other end of the high-impedance harmonic wave eliminator at the neutral point of the PT handcart module. The auxiliary device is mounted at the neutral point of the high-voltage side of a PT handcart, so that the tedious work for measuring the capacitance current of the power distribution network can be simple and clear, and operation exiting is not needed to be performed on a PT, and workload can be decreased, and work efficiency can be improved, and work security can be improved.