A review.20Th century, glutamic acid fermentation technol. has changed largely, basically, the production process of glutamic acid fermentation is divided into two categories: suboptimal dose isoelec. IX and temperature Sensitive concentrated isoelec.Because of the strict requirements of national policy and production costs, the suboptimal dose isoelec. IX shows its disadvantage.Aimed at the disadvantages of traditional process, some companies find a new method which is named "ultra suboptimal dose crystal transformation isoelec. IX".In this paper, two basic process routes and a new method which is derived from the two basic methods are discussed.We anal. the different processes through strain characteristics, extraction technol., extraction yield, contamination probability, downstream processing and production cost in order to summarize the advantages and disadvantages of each technol. which will promote the development of the MSG industry.