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

给出了在平面平行运，瞬的本与空间间关系的一种证明方法.

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

摘要给出了定点运本面与空间面间关系的一种证明方法。