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

给刚体在平面平行运动时，刚体瞬本体极迹与空间极迹间关系证明方法.

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

摘要给刚体定点运动时本体极面与空间极面间关系证明方法。