Abstract In pocket milling, there may be residual material left at sharp corners when stepover is inappropriately large in contour-parallel tool paths. According to this problem, the paper proposes an improved NC toolpath generation strategy in order to optimize NC machining processes for pocket milling. By inserting two types of biarc transition segments in contour-parallel toolpaths, the new method can remove the residual material completely without cutter compensation, produce second order continuous toolpath, and allow the stepover to be as wide as possible to reduce the machining time. A machining experiment has been implemented to validate the efficiency of the method.