The invention discloses a production method of grifola frondosa polysaccharide and relates to the technical field of food microorganism application. The method comprises the following steps of: weighing raw materials, wherein rice bran is 1-6g / 100mL, wheat bran is 1-3g / 100mL, monopotassium phosphate is 0.09-0.36g / 100mL, and magnesium sulfate is 0.04-0.16g / 100mL; adding a needed amount of water into the raw materials, loading the raw materials without regulating the pH (Potential of Hydrogen), and sterilizing and boiling at 121 DEG C for 30min; after cooling, inoculating the grifola frondosa liquid seed (CCTCC (China Center For Type Culture Collection) M2013286) which is also disclosed in the invention, wherein the inoculation amount is 8-10%, the fermentation temperature is 25-30 DEG C, and the fermentation time is 4-7d; and carrying out deproteinization, alcohol precipitation, centrifugal separation and vacuum drying on the centrifugal separation liquid of a fermented product or the centrifugal separation liquid which is obtained after the mycelia which has wall broken is extracted with hot water, so as to respectively obtain exopolysaccharide and mycelia polysaccharide. By adopting the method disclosed by the invention, the purpose of efficiently converting the rice bran and the wheat bran to the grifola frondosa polysaccharide with a high value through liquid state fermentation can be achieved better.