As one of Chinese four great classic novels, A Dream of Red Mansions, which is considered as the encyclopedia of feudal society, is of great value to be studied. Up to now, most researches mainly focus on the translation, cultural and pragmatic fields. When it comes to the investigation on the dialogue in this works, most researches just center on the leading roles in the novel. Whereas, attention paid to the subordinate figures such as Granny Liu. Taking Granny Liu’s typical dialogues extracted from the English version of A Dream of Red Mansions translated by famous translator Yang Hsien-yi as corpus, this thesis launched an exploration on how the subordinate figures Granny Liu carried out communication in the three aspects of RT respectively including the ostensive-reference process, context and cognitive environments, and the optimal relevance. Surely, this analysis can exert favorable influence on readers to evaluate Granny Liu more comprehensively and objectively, and also nudges readers to appreciate the exquisite and superb artistic charm of this novel and digest the writer’s creation intension. Meanwhile, this analysis is of substantial benefit to expand the research objective and field about Relevance Theory.