Various kinds of interference in the ultra-high voltage substations are significantly inferential to the linkage current measurement of surge arresters. In order to check the normal measurement of the linkage online current measurement of surge arresters, both electric field and magnetic field interference at power frequency is proposed in the lab tests. Under the electric field interference, the test results of linkage current are over the error of the nominal value on the plate of the device if the wires of the sensor are not shielded. However, using the shielding can avoid this electric field interference. Moreover, placement of the wires can obviously change the measurement results. Meanwhile, the level of change of the measurement data increases with the electric field interference.