2,4-difluoroaniline is an intermediate of organic synthesis. It is used for the synthesis of difluorophenylsalicylic acid and polyhaloperidic acid in medicine. Fluorobenzene salicylic acid is a kind of non steroidal anti-inflammatory drug of carboxylic acid, and the international non exclusive drug name (inn) is diflunisal. The new derivative of salicylic acid, does not contain acetyl group of aspirin, but contains difluorophenyl group, so it has little side effect on platelet and mild gastrointestinal reaction, and its action time can last for 8-12h. Therefore, it may be the most promising salicylic acid drug. It is also an important intermediate of pesticide.