Abstract: Dehydrated sword bean is an important dehydrated product in China Hand-seleting is a common method used by many vegetable dehydration factories. Bacterium from hand-selecting will make molds reproduce quikly during storage, which would affect the quality of products.Storage tests after different doses of irradiation (at 4,6,8 kG_y) were made. Four indexes,i, e, the contents of Chlorophyll, the contents of vitamin C,the number of molds and the number of bacteria measured against time of storage and different packing methods, Results showed that the best dose was 6kG_y,and the most suitable package material was compound plastic bag. Finally,the effects of irradiation on the structure of cells and original number of bacteria on sterilization were discussed. Conclusions were that dose at 8 kG_y had great effect on the structure of cells, and initial numbers of bacteria should be controlled under the level of 10⁴.