In this research, high efficiency machining tool path design of die cavities were developed using CAD/CAM and plunge roughing technology. The algorithms of cutting tool path design for ideal and non-ideal rouging area were proposed to improve the material removal rate (MRR). The proposed tool path design methods are based on the minimum numbers of rectangular or triangular patterns to cover the roughing areas. The cutting results of the traditional Z-plane and the plunge roughing were compared to show the improvement of the cutting efficiency with the proposed methods. Design of experiments (DOE) method was adopted to optimize the tool path designs and cutting conditions. Cutting experiments were carried out to verify the proposed cutting path design methods. The better material removal rate was obtained using the proposed plunge roughing method compared to the traditional Z-plane roughing. Both of the cutting simulations and the cutting experiments also showed the cutting efficiency of plunge roughing is increased with increase of cutting depth. The proposed hybrid tool path design method can further improve the cutting efficiency of plunge roughing process.