A special test circuit was designed to measure the transient current in time domain. The measurement was performed on 0.68Pb(Mg1/3Nb2/3)O3–0.32PbTiO3 (PMN-32%PT) single crystal. Abnormal transient current was observed in time domain. Two oscillations were observed in transient current. By means of discrete Fourier transform (DFT), two peaks were found in frequency domain, which were corresponded to the resonance frequencies measured by frequency domain method. This phenomenon can be attributed to piezoelectric resonance. The transient current was calculated and fitted well based on a piezoelectric resonance equivalent electrical circuit model. Experimental results confirmed that no oscillation can be observed in PMN-32%PT single crystal samples after thermal annealing, which also verified that the piezoelectric resonance was the origin of the abnormal transient current.