The utility model discloses a refining plant for amylohydrolysis liquid, include that membrane module (4), second refined cauldron (7) are held back to first refined cauldron (3), first molecule, membrane module (9) and finished product export pipeline (11) are held back to the second molecule, wherein, these first refined cauldron (3) are held back membrane module (4) with first molecule and are linked to each other, first molecule is held back membrane module (4) and is linked to each other respectively with first refined cauldron (3), second refined cauldron (7), the second is refine cauldron (7) and second molecule and is held back membrane module (9) and link to each other, finished product export pipeline (11) link to each other with second refined cauldron (7) for finished product output is regarded as to the refined result of second grade after refining the second grade. The utility model discloses an improve the connected mode of the refined cauldron of the two -stage of key, material endless form etc to set up aseptic filteration equipment, compare the continuous production that can effectively realize the specific molecular weight scope amylohydrolysis liquid under the germ -free condition with prior art.