With the development of science and technology, the more excellent surface quality of part is demand. But considering the complicated relation of machining parameters to surface roughness, the explicit analytical model has not been fingered out. Response surface methodology is introduced to build parameter sensitivity model corresponding to reliability of surface roughness to structure parameters of the tool. The results show that the tool nose radius and the approach angle are the dominant factors influencing the surface roughness, accounting for 56. 82% and 27- 84% of the surface roughness, respectively. Surface roughness is insensitive to rake angle. The rake angle only accounts for 9. 75% of the surface roughness.