The vapor flow behaviors are studied for a rotating heat pipe. The rotational speed ranging from 0 to 5000 rpm and the radial Reynolds number ranging from 4 to 24 are used as parameters. A two- dimensional and axisymmetric model is built and solved by SIMPLE method. The axial and the radial velocity fields are presented. The result shows that the high rotational speed causes main annular flows in the heat pipe. The influence of centrifugal force on the velocity profiles is decreased with the increase of radial Reynolds number. The result can provide design information for the related industries.