Last few decades have witnessed a growing interest in Adam Smith' s moral philosophy in worldwide scholarship. It is the same case in China. One indicator is the number of Chinese versions of The Theory of Moral Sentiments（TMS）in last fifteen years has increased to as high as more than 30. The large number of Chinese versions of TMS， however， does not guarantee the most thorough understanding of Adam Smith' s thoughts. On the contrary， some bad-quality translation has caused confusion instead of providing clarification. For example， the so-called ″das ′Adam Smith-Problem′,″ which has long been settled down in western scholarship， is still puzzling some of Chinese scholars. One possible reason that has led to this puzzlement is the improper Chinese translation of the title of TMS， which in turn is directly related to the understanding of the core of Adam Smith' s moral philosophy.  Besides， as a writer， Adam Smith is also famous for his responsible and strict attitude towards his own works. In one of his letters， Smith describes that he would write and rewrite five or six times to make himself satisfied with his own writing a little bit; and he made five revisions on TMS during his lifetime. What' s more，Adam Smith gives lectures on rhetoric and belles-lettres before he teaches moral philosophy. All these lead to the conclusion that in order to fully understand the theory of such a scholar， a detailed （even word-for-word） textual study of his works is a necessity. This thesis attempts to explore the core of Adam Smith' s moral theory through studying the diction of the title of his work The Theory of Moral Sentiments（TMS）． This article begins with the discussion of the origin of the title of TMS. With the help of a detailed textual analysis， the exact meanings of the key words in the title have been explored. If it is right that Smith has got his inspiration of the title from Levesque de Pouilly' s ″The Theory of Agreeable Sensations,″ why does Smith adopt ″sentiments″ to take the place of ″sensations″？ Are there any difference between ″sentiments″ and other terms related to feelings used in his work？ Why does Smith use ″the″ instead of ″a″？ How should ″the″ be understood with regard to Smith' s epistemological standpoint？ Is ″moral sentiments″ a neutral term with the meaning ″related to ethics″ or a positive term with the connotation of ″righteous; virtuous″？ Has Smith got different understandings concerning ″system″ and ″theory″？ All these questions have been addressed in the thesis． Special attention has been focused on the differences between ″sentiment″and its synonyms， such as ″emotion″、″affection″、″passion″. It has been pointed out that ″sentiments,″ as one of the key words in Adam Smith' s moral theory has two essential layers of meaning: one is that ″sentiments″ derive from our ″senses,″ which is the similarity shared by all the synonyms related to ″feeling″; the other is that ″sentiments″ are also the ability to make moral conceptions and judgments based on ″emotion″ ″affection″or ″passion.″ The first layer of meaning shows us the connection between Smith' s thoughts with the long-lasting tradition created by Hutcheson；while the second layer of meaning is more directly related to the core of Adam Smith' s moral philosophy and is what Smith emphasizes most in his illustration. It is more like a judgmental faculty or mechanism instead of just a responsive emotion. In a word，″sentiments″ is a word of a more abstract and higher level than the other synonyms related to ″feelings,″ and could be regarded as the basis of the daily judgements.  A comparison has also been made between the use of ″moral sentiment（s）″ in Adam Smith' s TMS and Hutcheson' s and Hume' s works. The frequency and specific contexts of the use of this phrase has been counted and explored. It has been found that both Hutcheson and Hume have used ″moral sentiment（s）″ more or less with a positive connotation， that is，″righteous; virtuous″ ；while Smith has adopted a neutral stance， taking it as an opposite to ″natural sentiment（s）.″ That is， to Adam Smith，″moral sentiments″ could be either ″virtuous″ or ″vicious″ in moral sense， and the psychological mechanism behind the moral judgment is the mechanism of ″sympathy,″ which is undoubtedly the core of Adam Smith' s moral theory． Based on these analyses， it is hoped that a thorough understanding of the connotation of the title could be achieved. The Chinese translation of the title ″The Theory of Moral Sentiments″ is always a disputable issue among the scholars. Although the two most popular translations，Daode Qingcao Lun（《道德情操论》） and Daode Qinggan Lun（《道德情感论》）， seem reasonable to some extent， from what has been discussed， we could make a safe conclusion that Daode Qinggan Lun（《道德情感论》） is indeed more faithful to the core of Adam Smith' s moral theory， since″Qinggan,″ compared with ″Qingcao,″ is a more inclusive and neutral term in Chinese．