Abstract: The paper focused on the influence of microwave Irradiation mutagenesis on Rhizopus oryzae F6.A high glucoamylase producing strain Rhizopus oryzae F6 was screend out from its parrent strain F6 by microware irradiation.Its saccharogenic activity increases by 3.7 times and its characteristics of highly producing glucoamylase remained stable after many times of subcultures storage for one years.