In the study of the history of bureaucracy, the retainer system of the pre-Qin Dynasty is a very important origin. However, the origin of this origin is still not clear, allowing people to understand the evolution of every type of official position. And through combing through the documents in Zuo Zhuan and Guo Yu, I found that the so-called "eunuch" in the commentaries of later generations and the meaning contained therein are essentially different, whether it is in body structure or It is the similarities and differences of functions. Therefore, the author gains a glimpse of the official official system by examining and distinguishing the "Zhu" and " Si Ren " in the two handed down documents.