The invention provides a method for enzymatically synthesizing 
astragalin. The method comprises the following steps that 1, key enzymes needed in the synthesizing process of 
astragalin are cloned, expressed and purified, wherein the key enzymes comprise 
glycogen phosphorylase GP, glucose pyrophosphorylase GalU, 
flavanone-3-hydroxylase F3H, 
flavanone synthase FLS1 and 
flavonoid3-O-glucanotransferase UGT78K2; 2, 
glycogen Gn is synthesized into glucose-1-
phosphoric acid G-1-P under the GP effect; 3, G-1-P is synthesized into 
uridine diphosphate UDPG under the GalU effect; 4, 
naringenin NRN is synthesized into dihydro 
kaempferol DHK under the F3H effect; 5, DHK is synthesized into 
kaempferol KMF under the FLS1 effect; 6, KMF and UDPG are synthesized into 
astragalin under the UGT78K2 effect. According to the method, few steps are adopted, the operation condition is mild, few side products are generated, the yield is large, 
pollution is avoided, and the production cost is remarkably reduced.