The invention discloses a method for producing 
potassium gluconate through 
fermentation of 
Aspergillus niger, which comprises the following steps: performing one-step jet on 
starch and 
starch-containing materials, and performing double-
enzyme glucose preparation; using an 
Aspergillus niger P1205X21 strain which is resistant to high-concentration K<+> to ferment the glucose solution, and feeding an 
ion membrane KOH solution in the 
fermentation process to obtain a 
potassium gluconate solution; and by using a 
thermal crystallization process of multiple-effect continuous 
evaporation and 
crystallization, directly evaporating and crystallizing in a multiple-effect 
evaporation crystallizer to obtain the 
potassium gluconate finished product. The invention has the advantages that the raw materials are rich and accessible, the cost is low, the 
fermentation product is simplex, the product quality is high and easy to control, no waste water and 
waste gas are generated, no 
calcium gluconate 
mother liquor and 
calcium sulfate waste are generated, the environmental 
pollution is greatly reduced, the process 
route is short, 
evaporation, 
crystallization, 
drying and other procedures during 
calcium gluconate preparation are reduced, vapor is saved, the 
power consumption is reduced, and the production cost is greatly lowered.