The behavior of flow between two coaxial frustum cones, with the inner one rotating and the outer stationary, is studied in this paper. It is found that the fluid at the outlet does not flow out directly, but flows up till a certain height. This reflux generates a vortex area with a quite large velocity and pressure magnitude. This reflux area, between Z/H = 0.05 and 0.30, has the trend to move up with increasing Reynolds number Re. The velocity magnitude is linear in the radial direction if the Re is small. This linear relation converts to quasi-quadratic function as the Re increasing. If the frustum cone inclination is small,the flow will tend to be unstable with a quite large velocity and pressure magnitude.Finally, a comparison is made with Taylor-Couette flow.