Abstract: Cutter selection is one of the most important tasks of NC programming.In order to improve efficiency and quality of NC machining and programming,an automatic cutter selection approach based on geometric characteristics was proposed according to the features of NC programming and rough machining of aircraft integral panels.Firstly,by analyzing the relationship between the cutter and its machinable area,the 45° draft of a profile was established by revising the domain of a voronoi mountain.Secondly,the calculating methods for machinable area,unmachinable area and the minimum radius of the cutter were presented;Lastly,the procedure for determining the optimal cutters was introduced based on the principle that the total time for machining pocket is the shortest.The proposed algorithms were developed and applied in a practical project.Resultsshow that the algorithms are feasible and valid.