Preliminary study on slicing technology and design theory of slicing cutter shows that there is deviation between the machined tooth surface and the theoretical tooth surface, called theoretical machining error. This deviation is affected by cutter parameters and machining parameters. To improve machining accuracy, a suitable combination of parameters should be ascertained. On the other hand, interference between major flank face of the cutter and machined tooth surface of the workpiece could occur with inappropriate parameters. In addition, the constraint conditions of enough addendum thickness and no top cut also raise a claim to parameter optimization. For this purpose, the mathematical model of theoretical machining error is built. The judgment method of interference is proposed. The mathematical discriminants of enough addendum thickness and no top cut are presented. On this basis, the selectable ranges of parameters are determined by the constraint conditions. Then, orthogonal experiment is carried out to select an optimal combination of parameters by analyzing the theoretical machining error. Machining experiment is performed with the selected parameters. The results prove that the proposed optimal selection method is effective and applicable.