The invention discloses a method for recovering 
coin protein sugar dregs and preparing 
protein nitrogen sources and 
nitrogen-containing syrup in the production of enzymatic 
corn starch sugar, comprising the steps of size mixing, liquefying, saccharifying, standing separation, 
centrifugal separation, 
proteolysis, concentration, 
drying, compounding, and the like. In the invention, 
protein is condensed under the heat flash of liquefying, the protein 
sugar dregs concentrate and float upwards in saccharifying, the sugar dregs are recovered through the steps of standing separation and 
centrifugal separation, the sugar dregs are dried into protein, or the sugar dregs are hydrolyzed to prepare 
protein nitrogen sources, and the 
nitrogen sources can be compounded with syrup to form nitrogen-containing 
starch syrup for fermenting. Clarified saccharification liquid after 
centrifugal separation is decolored, filtered, refined and concentrated, and 
starch syrup products are obtained. The majority of lentous sugar dregs in the saccharification liquid are removed before the treatment of decoloring and filtering, and the decoloring and filtering performance of the material is better. The use level of 
active carbon, and the like can be properly reduced, the production capability of filtering equipment is improved, and the frequency of the loading and unloading of filters as well as the consumption of washing waste water and various kinds of loss are greatly reduced.