Abstract: In this paper, the criterion for the judgment of stability of general mechanical system is discussed, and the calculation result shows that it is unreasonable using "System Dam-ping" for above purpose. The concepts of general energy and the principle of general energy concervation are elaborated in detail, and the ratio of general energy is used as the index to determine thestability margin of system.

Key words: 广义能量判据, 稳定裕度