Abstract: To insure the rotation of rolled parts is the fundamental condition for building normal rolling process in cross wedge rolling. Under the same technique, there will be a most difficult area to rotating the part, it is neither in the begining nor in the stretching shaping part of the wedge, it is around the highest point of the wedge from its begining where the rolled part rotates about half a circle (θ=π). It has been demonstrated by not only practice also the formulas of rotatory condition.