《论语·乡党》有“疾,君视之。东首,加朝服,拖绅”一章,何晏《论语集解》引包氏注认为“东首”的位置当在南牖之下,郑玄却认为应当在北墉之下。南牖、北墉正好是士人寝室中南北相对的两个不同位置。本文通过考查两种不同经说成立的根据,说明了郑玄“北墉下”经说的思考过程,揭示了郑玄经注的特点。 “Analects of Confucius Township Party” has “disease, monarchy. East first, plus North Korea served, drag gentry,” chapter, He Yan “Analects of Confucius” cited cited cited Note that the “east” position when the south Under 牖, Zheng Xuan believes that it should be under Beibei. Nanxun, Beibei happens to be the scholar bedroom relative to the two different locations. By examining two different bases for establishing the theory, this essay illustrates the thinking process of Zheng Xuan ’Beibei’ and tells the characteristics of Zheng Xuan Jing.