The invention relates to a potassium ferrate aqueous solution, a preparation method thereof and an application thereof as a deodorizing spray. The potassium ferrate aqueous solution per liter comprises the following components: 1.0-3.0g of potassium ferrate, 1.2-1.7g of sodium dihydrogen phosphate dehydrate, 4.0g of sodium hydroxide and one of 0.4-0.8g of glacial acetic acid, 1.9-2.3g of citric acid monohydrate, 2.4-3.2g of sodium carbonate and 0.5-1.0g of sodium hypochlorite. According to the preparation method, the other components are completely dissolved and then stabilizing liquid is acquired, and then potassium ferrate is added and is completely dissolved. According to the preparation method provided by the invention, the decomposition rate of potassium ferrate can be effectively reduced, the oxidability and selectivity of potassium ferrate are promoted and odors from amine compounds, and sulfur oxides and hydrides are eliminated.