《字鉴》是成书于元代的一部正字法之书，在我国文字学发展史上有着重要的地位。对《字鉴》所收录的正字与俗字进行研究，将有助于我们加深对异体字内涵、正字与俗字关系以及作者俗文字观的理解。本文的主要工作是通过对《字鉴》收录的约920组正俗字（因一字数形而含正字787字、俗字920字）进行穷尽性的分析，以科学的理论和方法为指导，以充足的文献材料为依据，考察每组正俗字事实上存在的字际关系，分析《字鉴》正俗字的判定标准，探明《字鉴》俗字正误判定标准，从而总结出作者的俗文字观。通过对每组正俗字事实上存在的字际关系的考察，我们认为正字与俗字间的关系可以是异体关系（俗字是正字的异构或异写），也可以是非异体关系（俗字是正字的分化字、通假字或其他）。他们本属于不同的范畴。《字鉴》正俗字的判定标准是：正字见于《说文》者，以合于《说文》者为正，以不合于《说文》者为俗；正字不见于《说文》者，以合于六书者为正，以不合于六书者为俗。《字鉴》对俗字的是非正误的判定是从字构和字用两个维度上进行的：大凡破坏正字原有构意的俗字、累加形符构成的强化形声字以及与他字同形的俗字皆被否定。通过这三方面的工作，我们总结出作者李文仲既开放又保守的俗文字观。

Zi Jian, a book on orthograph that came into being during the Yuan Dynasty, is conspicuously pivotal in philology of China. Studies on orthodox and popular form of characters included in Zi Jian will provide us a clearer view on the understanding of variant Chinese characters, relationship between orthodox and popular form, and the author’s perspective on the popular form of characters. The purpose of this paper is to present a relatively thorough analysis on the 920 pairs of characters written in both orthodox and popular form (787 of orthodox forms, 920 of popular forms, variants considered) listed in Zi Jian. The paper will be developing under the guidance of scientific theory and method, and built on adequate documentary sources. It aims at finding the relationship between the paired-up orthodox and popular forms, analyzing the criteria on which a character is seen as written in orthodox or popular form, providing an insight on judging whether a popular form is correctly written or not, and consequently summarizing the author’s perspective on popular form of characters. Based on observation on the pairs of orthodox and popular forms, this paper purports that the relationship between orthodox and popular forms could be seen both as origin-variant (popular form is a variant that stems from orthodox form) and as non –origin-variant (the popular form of characters is actually the form of relevant but independent characters, or Tongjia characters, etc). They came from different categories. The criteria on which a character is considered written in orthodox or popular form in Zi Jian is as follows: any character that appears in or conforms to that in Shuo Wen or Liu Shu is seen as in orthodox form, and vice versa. The judging rules adopted by Zi Jian in terms of whether the popular form is correctly written are established in two dimensions: structure and application. Denied are all the popular forms constructed by breaking down the original structure and meaning of the orthodox form, enhanced phonogram constructed by adding in extra pictogram, and characters exactly the same in form. This way, the conclusion that the perspective Li Wenzhong (author of Shuo Wen) holds on the popular form is both liberal and conservative is thus drawn.