Abstract: A second-order nonlinear neutral delay differential equation was studied, and some sufficient conditions for existence of positive solutions for this equation were established. The advantage of the results is omitting the restriction condition of for any， must be negative. Furthermore, some examples were presented to illustrated that the results is more effective.

Key words: Nonlineal ,  Neutral , Positive solution , Contraction mapping , Fixed point

摘要： 　    研究了一个二阶非线性中立时滞微分方程，给出了关于此方程正解存在的一些充分条件，其优点在于省略了对任意的ａ＞０，ａＱ_１（ｔ）－Ｑ_２（ｔ）都是最终非负的限制条件。最后通过数值例子说明研究结果的优越性。

关键词: 　非线性 , 　中立型 , 　正解 , 　压缩映射 , 　不动点