Carboxylic acids are widely used in industry and are considered an important type of chemicals. The production of carboxylic acids through oxidation of lignite is very promising. The traditional alkali oxygen oxidation of lignite can produce high yields of carboxylic acids, but the process consumes a great deal of alkali and acids and the high reaction temperature increases the energy consumption. In the present work, we found that carboxylic adds, including small-molecule fatty acids and benzene poly(carboxylic acid)s, could be obtained by Catalytic oxidation Of lignite in NaVO3/H2SO4 aqueous solution with molecular O-2 The effects of NaVO3/coal mass ratio, H2SO4 content, reaction temperature, initial O-2 pressure and reaction time on the conversion of lignite and Yield of carboxylic acid's were investigated. In the process of reaction, lignite is first converted into water-soluble intermediate; which are then converted into carboxylic acids. The second step is the rate controlling step. It has been found that in the catalytic system, sulfuric acid not only promotes the degradation of lignite, but also changes the activity of vanadium species. Vanadium species promote both the conversion of lignite and the generation of carboxylic acids. The presence of oxygen makes vanadium species complete redox cycle, keeping the reaction ongoing. Compared with the alkali oxygen oxidation, this catalytic oxidation method can reduce the usage of acid and alkali, and lower reaction temperature, while keeping the same yield. The Catalytic system was reused four times without decline in activity.