It is experimentally observed that PNN–PT ceramics processed with glycerol possess superior unipolar fatigue resistance; but the same ceramics processed without glycerol are vulnerable to unipolar fatigue. For PNN–PT–glycerol fatigued by 5 × 107 unipolar cycles, there are no losses in the maximum polarization (Pmax) and remnant polarization (Pr). But for PNN–PT, these losses are ∼14% and 22%, respectively. In addition, strain asymmetryγS and internal bias field Ebias of PNN–PT–glycerol are much less than those of PNN–PT. However, the ferroelectric properties can be recovered by bipolar cycles and thermal annealing; and such recovery is much easier and larger in PNN–PT–glycerol than in PNN–PT ceramics. Scanning electron microscopy micrographs show that the significant loss in properties of the fatigued PNN–PT ceramics is accompanied by a measurable number of severely damaged grains in the samples, especially in the region near the electrode surface, whereas the much less damaged grains in the PNN–PT–glycerol ceramics contribute to their good fatigue performance.