摘要
本文研究一般平面自治系统的非零周期解的存在性问题，获得了保证此系统存在非零周期解的充分条件，所得结果推广和改进了一些已知结论。
In this paper,the existence of periodic solutions for autonomous planar systemsis studied and sufficient conditions for the existence of non-zero periodic solutions of this kind areobtained.Some known results are extended and improved.
