When the drill bit is drilling in the ultra-deep well, the flow field is in 3-D turbulence. The revolving and the surface curvature effect of the drill bit, as well as the following coriolis force and the centrifugal force make the flow field extremely complex in the ultra-deep well. Simultaneously, because the fluid medium mud belongs to two-phase currents of fluid and solid, which makes the test of internal flow field more difficult. The fluid dynamics software-fluent is applied in the ultra-deep well, based on the Navier-Stokes equation and the Reynolds stress equation model, several models are built in the paper. In the same conditions, the different results are stimulated by CFD simulation software Fluent; relative designing geometry parameters are optimized.