Yao Xiaosui is a famous historical archaeologist and language philologist, who has made outstanding contributions in the fields of history, archaeology, linguistics and philology. He is an expert in philology, whose major works including Yao Xiaosui’s collected papers of ancient Chinese characters{《姚孝遂古文字論集》),The study on Xushen and Shuowenjiezi (《静慎與<說解字>》), Explanations on Bones and Tortoise Shells in the south of Xiaotun (《小屯南地甲骨考释》), The research on Inscription of Hu(《<留鼎>铭文研究》),Distinguish the tripot of Yu(《<御鼎>辨伪》],Distinguish the dagger of Chugongjia (《<楚公(?)戈>辨偽》). As a chief editor, his works including The Gathering of Explanations to Inscriptions on Bones and Tortoise Shells (《甲骨文字詁林》), The compilation of Inscriptions on Bones and Tortoise Shellsy in Yin Dynasty ruins(《殷墟甲骨刻辭類纂》), The sylloge of Explanations on Bones and Tortoise Shellsy in Yin Dynasty ruins(《殷墟甲骨摹释總集》), History of Chinese graphonomy (《中國文字學史》), etc.. This paper takes Yao’s works in philology as a main object to research. We come to the valuation of Mr. Yao’s great academic success in philology and give a more proper assessment, by the organized way of analyzing and inducing.This paper is divided into three parts. The first one is the concisely introduction of our topic. In this part, we introduce Mr. Yao’s life stories, which including his learning experience and attitude. At the same time, it will also illustrate Mr. Yao’s main woks and our study on goals, methods, significances, thoughts and the present situation from internal. Then following the second part, which consist of four small topics, explaining the results soughts by Mr. Yao separately about Inscriptions on Bones and Tortoise Shellsy, Inscriptions on bronze, The study on Shuowenjiezi and The theories of Chinese characters. According to Inscriptions on Bones and Tortoise Shellsy, on the one hand, we introduce three reference books and make an evaluation of the gains and losses. On the other hand, we illustrate the explanations on Bones and Tortoise Shells, including topicality explanations and comments. These comments are embodied in The Gathering of Explanations to Inscriptions on Bones and Tortoise Shells (《甲骨文字詁林》). Combined with the new research findings and make a fair judgement. When it turns to the Inscriptions on bronze, Mr. Yao who wrote The research on Inscription of Hu (《<曶鼎>铭文研究》), Distinguish the tripot of Yu(《<御鼎>辨伪》), Distinguish the dagger of Chugongjia (《<楚公(?)戈>辨偽》), laid particular emphasis on studying inscriptions and distinguishing bronze. Compared with other aspects, Mr. Yao’s has few productions on the brone. He puts up some new ideas in the paper of The research on Inscription of Hu (《<曶鼎>铭文研究》), these viewpoints should be paid more attention. The third topic is about Shuowenjiezi, for which The study on Xushen and Shuowenjiezi was written. This book makes a detail description on Shuowenjiezi including it’s stylistic rules and layout, author, research productions in the history, gains and losses of itself. Another topic is The theories of Chinese characters. We sort out Mr. Yao’s results and summarize some distinctive points on the basis of the theories, for example, characters development stages and the properties of Chinese characters, the relationship between pictures and words, study on the theory of Liushu, study on the Chinese characters of Yi, the irreversibility of the characters form of differentiation, the identities between language and characters, etc.. We certify these theories and make an objective assesment as far as possible. In general, the last part is the conclusions about Mr. Yao’s achievement and shortage.There are totally two results of this paper. First, it’s the first time to probe into Mr. Yao’s study on philology completely ever before. Furthermore, from the perspective of philology, by analysing Mr. Yao’s achievement and shortage of the study on Inscriptions on Bones and Tortoise Shellsy, Inscriptions on bronze, The study onShuowenjiezi and The theories of Chinese characters. We can provide some necessary references when assessing his philology achievement and weakness spreadly.