Abstract: When a permanent fault occurs on an AC line with DC infeed, if the fault characteristic cannot be precisely determined, the AC line will withstand the short-circuit current impact again, jeopardizing the safety of DC system operation. To solve this problem, a criterion of single-phase adaptive reclosure based on characteristics of harmonic current in fault phase of shunt reactor is proposed. Firstly, the applicability of the existing criterion of single-phase adaptive reclosure in AC systems with DC infeed is analyzed, and a conclusion is drawn that the harmonic component injected into the AC system after commutation failure of the converter can invalidate the existing criterion of single-phase adaptive reclosure. Moreover, through the fast ensemble empirical mode decomposition-Hilbert (FEEMD-Hilbert) spectrum analysis, the harmonic component is decomposed from the fault phase current of shunt reactor. According to different equivalent current loops under various fault characteristics, a novel criterion of single-phase adaptive reclosure based on amplitude ratio of harmonic current is proposed. Finally, the effectiveness and practicability of the proposed methodare verified by PSCAD/EMTDC simulation results.