Mg-Zr-O films for plasma display panels (PDPs) were deposited on glass substrates by magnetron sputtering method. The effects of Zr doping on both the discharge properties (firing voltage and the minimum sustaining voltage) and the microstructure of the Mg-Zr-O films were investigated. The results show that the deposited Mg-Zr-O films retain the NaCl-type structure as the pure MgO crystal. The grain of the films is very fine. The doped Zr exists in the form of Zr4+ substitution solution in MgO crystal. When the Zr concentration is about 2.03at%, the Mg-Zr-O films have the strongest (200) preferred orientation and the minimum surface roughness. The firing voltage and the minimum sustaining voltage of Mg-Zr-O protective films are reduced at most by about 25 and 15 V, respectively, compared with those of the pure MgO film.