本文从多方面改进了比较发散量积分法，利用这新方法给出了Ｌｉｅｎａｒｄ系统 极限环唯二性与唯一性的一些比以前更有效的判定条件．

In this paper, the method of comparision integral of divergence is improved in many ways. By this new method we give some more effective conditions which judge that the Lienard system has at most one or two limit cycles.