主述位理论是系统功能语言学的一个重要部分，主位不仅能帮助读者了解文章的中心内容，也反映了语篇的衔接与连贯，对翻译实践具有很大的应用价值。乔治•马丁的《冰与火之歌》系列作为奇幻小说的代表一经问世便深受全世界读者的喜爱和追捧，其汉译本更是为该系列在中国的传播奠定了基础，成为中外文学交流的优秀范本。本文在韩礼德系统功能语言学理论的指导下，分析奇幻小说《冰与火之歌：权力的游戏》第一章及其对应汉译本中的主位选择，以探究在翻译实践中译者对于英文主位的处理方式及原因，使语言学理论可以更好地服务于英文小说的汉译实践。根据小说文体的特点，本研究将小说语料分为叙事部分和直接引语部分，并各自探究了在不同语气结构下译者对主位的翻译方法。本研究发现，在处理原文的主位时，译者主要采用了保留原始主位、主位错位、更改主位类型以及主位的增删这几个翻译策略。同时，研究者从英汉语言固有差异的角度分析了造成主位偏离的原因。

Thematic Theory is an important part of Systemic Functional Linguistics. Theme not only helps readers to understand the main content of the text, but also contributes to the coherence of the discourse, which is of great value to translation practice. 
George. R. R. Martin’s A Song of Ice and Fire series, as a representative of fantasy novels, has been loved and sought after by readers all over the world, and its Chinese translation has promoted the dissemination of the series in China, which serves an excellent model for the exchange of Chinese and foreign literature. Following Halliday’s Systemic Functional Linguistics, this thesis analyzed the thematic choices in the first chapter of A Song of Ice and Fire: A Game of Thrones and its Chinese translation, with the aim to explore how the translators deal with Theme in the translation of the novel. According to the generic feature of the novel, the material is divided into narration part and direct speech part and the translation methods are investigated in respect of different moods in each part. It is found that the translation methods of themes mainly adopted by the translators include: retaining the original Theme, dislocating the Theme, changing the type of Theme, and adding or deleting the Theme. Factors that cause the deviation of Theme are also discussed from the perspective of the inherent differences between English and Chinese languages. It is hoped that this study can shed light on the practice of translating English fantasy novels into Chinese.