Abstract: The effect of hydrogen on the conductivity of PZT-5H ferroelectric ceramics was investigated by experiment and first-principles calculations.The resistivity of PZT-5H ferroelectric ceramics decreases with the increase of the content of hydrogen doped into the ceramics.When the total hydrogen content is 11.2×10^-6,the resistivity approaches to 1.51×10⁹Ω·cm,which is between the semiconductor and insulator.Further increasing the hydrogen content,the PZT-5H ceramics become an n-type semiconductor from the Hall effect.The results of first-principles calculations show that the Pb(Zr_0.5Ti_0.5)O₃₃₂H system,with the hydrogen content of 96×10^-6,becomes a semiconductor.The density of states (DOS) moves toward the lower energy with the increase of hydrogen content.The Pb(Zr_0.5Ti_0.5)O_3nH system becomes a conductor while the hydrogen content is larger than 96×10^-6.