Abstract: In order to obtain a high yield and stable naringin enzyme producing bacteria,taking the 36 strains of Aspergillusnigeras the experimental material,a strain of naringinase production strain M53 was obtained by conventional screening methods. A mutational strain named M53- 7 was bred through multiple mutagenesis( Li Cl treatment and UV irradiation).The culture medium of M53-7 was optimized by orthogonal experiment. The results showed that the optimal parameters for the fermentation culture medium were as follows: sugar 0.5%,soybean meal 3.0%,NH_4NO_31.0%,K_2HPO_40.1%,Ca Cl_20.1%,Mg SO_4·7H_2O 0.5%,Zn SO_40.1%.Under the optimum conditions,the enzymatic activity of M53-7 was 906.28 U / m L.The research proved that the M53-7 was born with the stable performance at naringinase- producing,and it can be utilized in industrial production.