In the valve-side busing of the UHV converter transformer,a capacitor-type bushing tap voltage divider is installed.In order to transmit the valve-side voltage to the control and protection equipment,after the converter is charged,a voltage transformer is connected to the bushing tap.During the actual operation,it was found that the ferro-magnetic resonance phenomenon occurred between the bushing tap capacitor and the voltage transformer of the converter valve side bushing,which may lead to the malfunction of the converter transformer in charging state.The article carries on the harmonic analysis based on the actual transiet fault recording,and obtains the characteristic frequency of the resonance.By analyzing the electrical principle of the voltage divider and voltage transmitter of the bushing tap,a transient simulation model is built,and the working condition of the ferroresonance is reproduced by using PSCAD/EMTDC simulation.Based on the theoretical analysis,the concrete measures of improving the voltage divider to avoid the resonance are put forward.