Preparation method of high-stability aminomethylbenzoic acid injection

A preparation method of a high-stability aminomethylbenzoic acid injection belongs to the technical field of medicines and comprises preparation of p-iodobenzylbenzoic acid and preparation of aminomethylbenzoic acid. According to the method, in the preparation process of p-iodobenzylbenzoic acid, edetate disodium is added to be matched with potassium permanganate to reduce the adding proportion step by step, impurities in a reaction system can be well removed, meanwhile, the reaction system cannot be affected, a large number of impurities cannot be introduced in the later stage of the reaction, and the purity of p-iodobenzylbenzoic acid is improved; in the preparation process of aminomethylbenzoic acid, the added PAM anionic flocculant can be further complexed with metal ion impurities to generate solid precipitates, the solid precipitates are re-suspended in hot water, solid impurities can be well removed through hot filtration, filtrate is purified, high-purity aminomethylbenzoic acid is separated out at a