In this paper, the electromagnetic disturbance of the voltage transformer arranged inside the switchgear is measured at the moment of switching operation. Then the characteristics of the disturbance waveform are analyzed. The measurement results show that the peak voltage of disturbance can be as high as about 120V, and the frequency does not exceed 25MHz. At the same time, the voltage transmission characteristics of the voltage transformer are obtained based on the experimental data. It is found that the transfer function of voltage transformer remains stable in the low frequency (below 50 kHz), and rises in the high frequency (above 50 kHz). This makes high frequency disturbances easier to affect its secondary side through the transformer. Finally, a filter design method is proposed for electromagnetic disturbance of voltage transformers. It is used to inhibit the high frequency disturbance above a certain frequency through the transformer to the secondary equipment, and it does not affect the signal below this frequency.