The harmonic likely to be induced by AC filter switching in high-voltage direct current（HVDC）is analyzed.This paper reveals the mechanism of the harmonic current causing series and parallel resonance that leads to harmonic amplification.According to the grounding features of the cable in the converter station，the inductive coupling interference due to this harmonic is analyzed.A case of real interference wave induced by the AC filter switching is used to validate the correctness of the above analysis.Further，some methods are proposed to solve the problem by improving the shield of secondary cable and increasing the action power of the intermediate relay to improve the reliability of the protection device.The system design and phase selection system are optimized to reduce the excess impact during filter switching.