The relationship between polhode and herpolhode of the instant center of a rigid body when it makes a plane paraller motion is presented.

给出在平面平行运动时，瞬本极迹与空间极迹间一种证明方法.

A certification method to the relationship between polhode cone and herpolhode cone is given when the rigid body is in a fixed point motion.

摘要给出定点运动时本极面与空间极面间一种证明方法。