Influences of sintering temperature on microstructure and electrical properties of TiO2 varistor ceramics were investigated. Morphologies of TiO2 ceramics samples were characterized using scanning electron microscope. The phase composition and crystal structure were researched by X-ray diffraction. The frequency dependences of the samples capacitance were determined using LCR meter, the varistor voltage V1mA and nonlinear coefficient α were discussed by experimental method. The results showed that TiO2 ceramics sintered at 1350°C for 2 h possesses fine microstructure and optimal electrical properties. However, the electrical properties of samples will deteriorate as excessive sintering temperature.