Due to their complex geometries, sculptured surface parts should be machined with multiple cutters of optimal sizes for high quality and productivity. Current methods of determining cutter sizes, however, are conservative and inefficient; their repeating process includes subjective cutter selection, intensive tool-path generation, and time-consuming gouging-and-interference detection in simulation. Our research proposes a new intelligent approach to multiple standard cutters of maximum sizes for three-axis sculptured surface machining. An innovative generic model of maximum allowable cutters in three-axis surface milling is built to eliminate any cutter causing local gouging and global interference. After the optimum standard cutters are automatically selected, their accessible regions can be identified, and the corresponding tool-paths can be generated, respectively. This approach is practical and effective in the process planning for three-axis milling of sculptured surface parts.