The characteristic of the structure ^ machining and mechanics as well as the problems in practical cutting, of whole hard alloy Gundrill, were analyzed in this paper. Besides, we educed the law which the cutting parameters affect the axial force and the torgue by experiments on SOB steel with the hard alloy Gundrill. furthermore, the theoretical explanation is also made. At the same time, we also analyze the cutting mechanism of whole hard alloy Gundrill. On the basis of comprehend of deep-hole drilling, we using VC++6.0 exploitation Solidworks 99. The CAD system of deep-hole drilling is founded.