中文摘要：

讨论了一类中立型退化时滞微分方程的周期解的存在条件,并且给出了二维退化滞后微分方程的周期解的存在性问题,且给出了一个充要条件和两个充分条件,最后举例说明结论的有效性。

英文摘要：

The existential conditions of periodic solution of singular neutral differential equation with delay are investigated.Particularly,the problem of existence of periodic solution of two-dimensional singular differential equations with delay is presented,and several sufficient and essential conditions are obtained.At last,an example is given to illustrate the proposed method.