Catalytic oxidation is an effective way to treat volatile organic compounds (VOCs), whose core is to develop stable catalysts with low temperature and high efficiency. Based on this, the catalyst of CoAl₂O₄ was prepared using metal nitrate as raw materials by the method of sol-gel. The optimum preparation conditions and optimal evaluation conditions were investigated, including calcination temperature, gas flow rate, catalyst dosage and evaluation temperature. X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area analysis (BET), thermogravimetric analysis (TG) and X-ray photoelectron spectroscopy (XPS) were used to explore the reasons for the high catalytic activity of the catalyst. The results show that the catalyst of CoAl₂O₄ has the best catalytic effect on ethylbenzene when the calcination temperature is 700℃. And the temperature (T90) reaches 311℃ when the conversion of ethylbenzene is 90%. Besides, the catalyst of CoAl₂O₄ has high catalytic activity, and the conversion of ethylbenzene is more than 96%，when the gas flow rate is 20 mL/min, the amount of catalyst is 0.2 g and the evaluation temperature is 400℃.