The invention relates to a graphite oxide with multiple carbonyl functional groups and a preparation method thereof. The operation is simple, safe and environmentally friendly. The obtained graphite oxide will not introduce new impurity elements, ensuring the use effect of graphite oxide. Compared with the Hummers method, there is no sodium nitrate in the reactant, and the generation of toxic gases nitric oxide and nitrogen dioxide is avoided. . The use of low-concentration fuming sulfuric acid in the reaction system can effectively absorb the moisture produced by the reaction, ensuring that there is no moisture, no hydroxide and hydrogen ions in the reaction system, so it can ensure that the oxidant potassium permanganate functional group introduced on the graphite base surface does not It will be replaced by hydroxide. Since the volume and mass of the potassium permanganate functional group are much larger than the hydroxide, the steric hindrance generated by the adjacent potassium permanganate functional group on the graphite base surface becomes larger, reducing the stability of the carbon-carbon bond. The carbon-carbon bond is broken, and the carbon atom is further oxidized to form two carbonyl groups, and the carbonyl content in the final product graphite oxide is significantly increased.