Abstract: To investigate the effect and mechanism of low frequency electromagnetic field(LF-EMF)on enzymatic reaction,in this paper,the hydrolysis of corn starch catalyzed by α-amylase was used as a model reaction,treatment on the reaction with 60 Hz LF-EMF was carried out. Based on the analyzing of the LF-EMF’s influence on the reaction efficiency of enzymatic starch hydrolysis,and its influence on the substrate structure,the enzyme structure and the mass transfer in solution system,the mechanism of the LF-EMF’s influence on the enzymatic reaction was discussed preliminarily. The results showed that LF-EMF radiation promoted the hydrolysis of starch catalyzed by α-amylase,14.39 mg/mL hydrolyzed sugar was produced in 10 h reaction,which was 15.90% higher than the control(12.41 mg/mL)(p<0.05);Neither remarkable change on the primary structure of α-amylase,nor irreversible change on the secondary structure/tertiary structure resulted from LF-EMF radiation was observed(p>0.05). The LF-EMF could reduce the optimum ionic strength(which was 0.0947 mol/L)of the α-amylase’s reaction system,and weaken the inhibition of high ionic strength on the enzymatic reaction. The sodium chloride diffusion experiment indicated that LF-EMF could promote mass transfer in solution system,the enhancement factor of ion diffusion was 1.23,and the apparent film thickness decreased significantly from 1.26 cm to 1.08 cm,which was 14.29% thinner(p<0.05). LF-EMF radiation improved the reaction efficiency of enzymatic starch hydrolysis catalyzed by α-amylase,one of the reason should be the enhancement of mass transfer,but the possibility could not be excluded that the LF-EMF radiation might affect the enzyme’s conformation and thus increase its activity.