This paper study the selection of machining condition based on stable lobes diagram to produce surface roughness. Firstly, the dynamic response of the machine tool is measured by hammer test, and then the stable lobes diagram curve can be found using the measured response. Next, a series of machining tests are executed based on stable lobes diagram curve. The tests use the same cutting depth, cutting width, and feed per flute. The spindle speeds distribute from one lobe edge to another. The machining signals are also recorded. Finally, the surface roughness of all samples is inspected to discuss the influences of spindle speed.