High speed CNC machining relies on the smooth interpolation of tool path in order to prevent impact and vibration. We present a new interpolation scheme for CNC controller based on 6-point subdivision. The subdivision interpolation improves the smoothness of the original trajectory, while maintaining the accuracy. The algorithm is simple and effective, and therefore it is suitable for real-time execution in CNC controllers. Simulation results show that the proposed method performs better than linear interpolation, since the tracking error and contour error is reduced.