The microstructure and electrical properties of ZNR that W O 3 is added in the range 0.5~4.0mol%, were investigated. The major part of W O 3 were segregated at the nodal point and W-rich phase was formed. Three crystalline phases, such as W-rich phase (W O 3 ), Bi-rich phase (B i 2 W O 6 ), and spinel phase (Z n 2.33 S b 0.67 O 4 ) were confirmed to be co-existed at the nodal point The average grain size increased in the range 15.5~29.9 μm with increasing W O 3 additive content. Consequently. W O 3 acted as a promotion additive of grain growth. As the W O 3 additive content increases. the varistor voltage and the nonlinear exponent decreased in the range 186.82~35.87V/mm and 20.90~3.34, respectively, and the leakage current increased in the range of 22.39~83.01 uh. With increasing W O 3 additive content, the barrier height and the density of interface states decreased in the range 1.93~0.43eV and (4.38~1.22) × 10 12 cm 2 , respectively. W O 3 acted as an acceptor additive due to the donor concentration increasing in the range (1.06~0.38) × 10 18 /㎤with increasing W O 3 additive content.