The invention relates to a method for converting
stevioside or rubusoside raw materials into
steviol by utilizing Aspergillusaculeatus ZJ (the preservation number of which is CCTCC No:M2011264) bacterium and enzymes thereof, and purifying
rebaudioside A (RA). The method specially comprises the steps of: acting Aspergillusaculeatus or
fermentation liquor thereof or extracted
enzyme liquor on the
stevioside or stevia rabaudiana extract liquid, and converting ingredients, except RA, of the
stevioside to product
steviol;
settling and separating the
steviol from the solution; purifying and separating by adopting a conventional
crystallization and other
purification methods, wherein the RA in the
system is not converted and left in the solution; and purifying the RA by adopting the following convention extracting, separating and purifying method. The invention provides a method for converting stevioside into steviol by utilizing Aspergillusaculeatus bacterium and
enzyme liquor thereof, and purifying
rebaudioside A. According to the method, the conditions are mild, the environment compatibility is good, and the
process equipment is simple, thus application values are high.