The invention discloses a fermentation technology for increasing content of glutamic acid. The fermentation technology includes following steps: preparing a protein material, preparing a koji and performing hydrolysis. A high-yield glutaminase microorganism is added when the koji preparing process begins or after the koji preparing process beginning, wherein an adding amount of the high-yield glutaminase microorganism is 103-107 per gram of the koji. In the fermentation technology for increasing the content of the glutamic acid, a mixed koji preparing operation is carried out through addition of the high-yield glutaminase microorganism on the basis of a distiller's yeast preparing technology of soybean sauce to obtain a high-glutaminase-content protein koji. A high-umami seasoning sauce, in which the content of the glutamic acid is more than 30g/L, is obtained through naturally sun-treatment or thermal-insulation fermentation in large pots and then through a squeezing process and a heating and filtering process. The method is free of a complex process in which a large amount of microorganisms is added during the hydrolysis process in the prior art, is simple in producing processes, reduces an invested cost of addition of glutaminase during the hydrolysis process, and can increase production benefit.