Abstract: For a closed short cylinder in a high-speed rotational condition, the max. Mach number reaches about 7 in the flow field. The equilibrium state of the flow field in this condition is a very important problem, which requires to be solved inevitably in some engineering. A method of numerical analysis was used in this study. A cylindrical coordinate system, a second-order upwind scheme, and the total energy model were also employed. The flow field of a short cylinder in closed and high-speed rotational condition was studied by 3D numerical method. The preliminary study shows that physical results can be obtained only in certain computing condition. In this case, the flow field of the short cylinder in closed and high-speed rotational condition is able to maintain rigid body rotational state when it reaches equilibrium state.