Abstract: In allusion to the inexistence of standard dose setting method for microbe control process of non-medical supplies such as food or medicine, a practical method is studied and discussed in this paper. In this method, product is irradiated by step dose based on the initial microbe load and object microbe load, then the resulted microbe load is obtained after each irradiation. The Polynomial fitting method is then used to obtain the relational expression between DM and radiation dose. The results show that for non-medical supplies irradiation such as food cubic fitting or four-order fitting should be used. Though five or higher order polynomial fitting is used in some literature, some error may occur for higher order than four in the non-medical supplies. The cause is that the radiaiton dose for most non-medical supplies is rather low, so within the range of accurate dosemetry the point of step irradiation is much fewer. This dose setting method has been used in the real irradiation process and satisfying results has been achieved,which indicates this method is useful for dose setting in nonmedical supplies irradiation. This study is meaningful for accurate dose setting and for reducing unnecesary irradiation dose.