The invention discloses a zinc oxide varistor. The zinc oxide varistor is made from the following raw materials in parts by weight: 95-105 parts of zinc oxide, 3.8-4.8 parts of bismuth trioxide, 1.0-1.5 parts of cobalt sesquioxide, 3.2-4.2 parts of antimonous oxide, 0.5-1.2 parts of manganese carbonate, 0.4-0.8 part of chromium sesquioxide, 0.01-0.035 part of silica, 0.05-0.12 part of nickel sesquioxide, 0.05-0.02 part of stannic oxide and 0.1-0.4 part of calcium carbonate. The invention also relates to a preparation method of the zinc oxide varistor. The zinc oxide varistor disclosed by the invention is reasonable in formula and proportioning, simple in production method and strong in operability. The main index parameters of the zinc oxide varistor disclosed by the invention are excellent, and the maximal control voltage, residual voltage ratio, flow capacity, leakage current, voltage temperature coefficient, current temperature coefficient, nonlinear voltage coefficient, insulation resistance, static capacitance and the like of the zinc oxide varistor hold an advantage in the similar products.