The invention provides a method for increasing the utilization efficiency of ozone and reducing the COD of wastewater. According to the method, a chemical agent for removing a hydroxyl radical capture agent generated in base catalysis ozone advanced oxidation is added into the wastewater so as to achieve the purposes. Calcium ions, barium ions and the like are added into a base catalysis ozone oxidation system, so that the hydroxyl radical capture agent becomes precipitate to be separated from the water and loses the capacity for capturing hydroxyl radicals, and accordingly the utilization efficiency of ozone is improved. In addition, part of organic acid generated by the calcium ions, the barium ions and the like and the ozone oxidation wastewater precipitates to be separated from the water, so that the consumption of ozone is reduced, and the utilization efficiency of the ozone treatment wastewater is indirectly improved. By means of the method, the reaction rate of ozone can be obviously increased, the utilization efficiency of ozone can be obviously improved, reaction time can be shortened, cost can be reduced, organic matter in the wastewater can be thoroughly mineralized, and the COD and the total phosphorus content of the wastewater can be significantly reduced.