The DC transmission system equipped with dynamic reactive power compensation devices has reactive power inversion characteristics, which could contribute to the transient overvoltage of the AC system when commutation failure happens. Firstly, the transient voltage of the DC transmission system is spectrally analyzed and its harmonic dominant frequencies are acquired. Secondly, the phase frequency characteristics of the SVC control system are analyzed, which reveals the internal mechanism of SVC hysteresis properties. The SVC hysteresis characteristic is the root cause of SVC reactive power inversion when commutation failure happens. On this basis, the control strategy for SVC capacitor switching is proposed. Part of the capacitors is removed during the recovery of the voltage, thus effectively suppressing the SVC reactive power inversion. Finally, the simulation results verify the effectiveness of the SVC control strategy.