The invention discloses a process for producing 
starch sugar. The process comprises the following steps of: pulp-conditioning edible 
starch; liquefying; passing liquefied 
starch through a primary floating 
clarifier, guiding an upper floating 
sugar dreg liquid into a primary 
buffer tank, and then entering a primary disc-type 
centrifuge to be centrifugated and separated so as to extract 
sugar dregs; combining a clear sugar liquid flowing out of the primary disc-type 
centrifuge and a clear sugar liquid flowing out of the primary floating 
clarifier and flowing into a saccharifying tank to be saccharified into a saccharified liquid; passing the saccharified liquid through a secondary floating 
clarifier, guiding an upper floating sugar dreg liquid into a secondary 
buffer tank, and then enteringa secondary disc-type 
centrifuge to be separated so as to extract sugar dregs; combining a clear sugar liquid flowing out of the secondary disc-type centrifuge and a clear sugar liquid flowing out ofthe secondary floating scum clearing device and filtering by passing through a membrane micro-
filtration system; and flowing a micro-filtered concentrated liquid containing dregs back to the secondary 
buffer tank, entering a micro-filtered clear sugar liquid into an 
ion exchange 
system to be decolorized and desalted, and then finally concentrating into a product. According to the process for producing the starch sugar disclosed by the invention, filter aids and 
activated carbon are not required in the clarification and the 
filtration processes, and high-purity sugar liquid can be obtained through the efficient operation of 
solid-liquid separation equipment; and meanwhile, sugar dregs without the filter aids and the 
activated carbon are extracted and can be used as a feedstuff raw materialfor animals, thereby changing waste into valuable, and no 
discharge of filtered 
solid wastes during the whole process exists.