Four kinds of Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 ferroelectric ceramics with different porosities are prepared, and the porosity effects on the depoling characteristics of those samples under shock wave load are investigated. The results show that under short circuit condition, the releasing current waveforms are in the form of square pulse for all samples. The amplitude of the current pulse decreases, but the width increases with the porosity increasing. The releasing charge decreases with the porosity increasing, which is consistent with the measurement by P-E loop. Porous ceramics has lower shock impedance, which improves the impedance match to the encapsulation medium. The depoling characteristics of those samples under high resistance load are simulated well by Lysne model. The results reveal that the dielectric constant of the sample is 4—5 times larger than that under static state, moreover, it decreases with porosity increasing. After the shock wave passing through the sample, the discharging time constant increases with porosity increasing. As the load increases, the rising edge becomes less steep for the restrain of the ferroelectric phase-antiferroelectric phase transformation under high electric field, and the breakdown happens to the dense ceramics.