WO3-based capacitor-varistor ceramics doped with Er2O3 were prepared and the microstructures and nonlinear electrical properties were investigated. The results show that there exist second phase Er10W2O21 on the surface of WO3 grains. Doping Er2O3 in WO3 ceramic can inhibit the grain growth. A small quantity of Er2O3 can significantly improve nonlinear properties of the samples. The permittivity of doped samples was higher than that of the undoped, and the high permittivity makes Er2O3-doped WO3 ceramics be applicable as a kind of capacitor-varistor materials.