Relating to the technical field of organic synthesis, the invention discloses a 3, 3', 4, 4'-oxydiphthalic dianhydride and 9-oxo(oxa)fluorene dianhydride composition, a preparation method and application thereof. The composition includes 3, 3, 4', 4'-oxydiphthalic dianhydride and 9-oxo(oxa)fluorene dianhydride in a mass ratio of 70-95:5-30. The composition provided by the invention can be prepared into high performance polyimide, which is far superior to polyimide synthesized purely from 3, 3', 4, 4'-oxydiphthalic dianhydride as the raw material in the aspects of tensile strength, heat resistance, mechanical strength and other performance. Through selection of an etherification reaction catalyst and a solvent, the invention provides a preparation method of the3, 3', 4, 4'-oxydiphthalic dianhydride and 9-oxo(oxa)fluorene dianhydride composition, and the method has the characteristics of simple operation, high product purity, low emission of "three wastes", and easy industrialization, thus having great application prospects.