Abstract: Glutamic acid has emerged as the largest amino acid product in the world, it has important applications in medicine, food and agriculture. Corynebacterium glutamicum is the most important strain for industrial production of glutamic acid. After the discovery of C. glutamicum, these are some achievements on the mechanism of glutamate overproduction at home and abroad. In this paper, the research progress of the three levels of mechanism, namely, gene transcription level, key enzyme activity, cell membrane and transport protein structure during fermentation was reviewed, the mechanism of glutamate overproduction was analyzed. In the future research, in order to complete the mechanism of glutamate overproduction, it is necessary to study the physiological effects and regulatory factors. If it's perfected, the research will provide a reference and direction for further improving the production of glutamic acid and research of developing microorganisms to synthesize other biological products.