Polar domain boundaries in non-polar antiferroelectric crystals exhibit emergent tunable polarity, yet some fundamental questions remain to be answered—particularly the origin of the domain boundaries. Here, in antiferroelectric Pb(Zr,Ti)O3 crystals, through temperature-dependent second-harmonic-generation microscopy and x-ray diffuse scattering, we reveal that the domain-wall characteristics change actively at temperatures more than 100 K lower than that of the antiferroelectric phase transition. This observation indicates that the previously considered domain wall can be a local object. Its occurrence is associated with the competition of polar and antipolar arrangements. These findings provide a better understanding of domain boundaries in antiferroelectrics and suggest a potential control strategy for engineering polar domain boundaries in non-polar crystals.