当用机器人多指手抓取任意形状的物体时，为了保证抓取的稳定性，合理地规划抓取接触点的布局是必要的。提出了一个评价抓取稳定性的性能指标，并证明了这一指标具有相似不变性。该指标与力椭球的体积成正比，可定量地描述抓取的稳定性程度，也适用于自适应夹具规划。给出的实例表明，提出的性能指标正确可行。 When robotic multi-fingered hand to grab any shape of the object, in order to ensure the stability of the crawl, a reasonable plan to capture the layout of the contact point is necessary. Proposed a performance index to evaluate the stability of grabbing, and proved that this index has the same invariance. This index is proportional to the volume of the force ellipsoid, which can quantitatively describe the degree of stability of grasping and is also suitable for adaptive fixture planning. The examples given show that the proposed performance indicators are correct and feasible.