There are many inclined holes in modern manufacturing industry. Due to the special machining state of drilling out, the drilling jigs and other auxiliary mechods can not been used. There is intermittent cutting for a long time during drilling out, and the axial force and torque are also impact force, which cause the drill to break. The experiments results showed that the axial force and torque were also been incresed, especially the later, which is the principal factor of the drill fracture. So it is the experimental foundation for further to control and protect the dill to break.