In machining practice, the selection of the tooling condition of the cutters is an important task for milling operation with better surface quality and material remove rates. This study was therefore aimed to evaluate the influence of the tooling condition, such as the flutes and overhang length, on the machining efficiency of a milling machine by using the machining stability analysis method. Essentially, the machining stability was calculated based on the measured frequency response functions of the milling cutter, while it was also affected to change by the changing milling tooling path. Therefore, the machining stabilities in different feeding directions, referred as polar stability boundary, were evaluated to show the strength and weakness of a specific cutter in contouring machining. The current results show that the overhang length greatly affects the dynamic characteristics and the limited cutting depths of the milling cutter. The stability boundaries of the machining conditions can be enhanced by appropriately adjusting the overhang of the milling cutter. Besides, the 2-flute cutter shows a larger cutting depth for surface contouring as compared with the 4-flute cutter, which is expected to increase the material remove rate under stable machining. As a whole, this study provide the valuable references for enhancing the machining efficiency through the use of different tooling conditions.