Purification method and preparation method for carbonyl fluoride

The invention provides a purification method for carbonyl fluoride. The purification method comprises the steps that purifying gas is used for reacting with impurities in gas of a crude carbonyl fluoride product to remove the impurities in the gas of the crude carbonyl fluoride product, wherein the purifying gas is any one or more of ClF, ClF3, ClF5 and F2. According to the purification method, the crude carbonyl fluoride reaction product is purified, any one or more of ClF, ClF3, ClF5 and F2 are adopted as the purifying gas to react with the crude carbonyl fluoride reaction product in a purification device, various impurities, especially CO2, CO, H2O, phosgene COCl2, N2O and the like, except carbonyl fluoride are removed, and the content of impurities is greatly reduced. In purified fine carbonyl fluoride gas, the purity of COF2 is larger than or equal to 99.95%, the content of CO2 is smaller than or equal to 150*10 (the volume ratio), and the content of COCl2 is smaller than or equal to 150*10 (the volume ratio).