Cultural factors very often cause great difficulties in translation. Cultural default is defined as an absence of relevant cultural background knowledge shared by the source text author and the intended reader who are from different cultural backgrounds. If the target reader have different cultural background knowledge, they might have difficulties understanding the cultural default elements in translation. Hence, the translator has to think of ways to solve the problem. Up to now, although there are many researches about translation of cultural differences, not many of them discuss the issue in relation to relevance theory. This study attempts to investigate translations of cultural defaults and discuss the phenomena from the perspective of the optimal theory suggested by Sperber and Wilson (1986). According to Sperber and Wilson, translation is an act of communication across language boundaries, the translator is expected to fill up the cultural vacancy and adopt different translation strategies to achieve optimal relevance. Our research questions include: how does the translator deal with the problem of cultural default? What kinds of translation strategies and methods does he/she usually apply in handling cultural default elements? What possible factors are there behind the translator's decision making? The object for the study is Auspicious Blessings Chinese New Year Prints from Yangliuqing, the book on the Chinese culture published by Cultural Affairs Bureau of the Macao S.A.R. Government and Macao Museum in 2007. Eleven texts from the book and their translations of picture captions are examined, the translator's strategies and methods are analyzed and the reasons for the strategies and methods are discussed. It is found out that providing adequate contextual effects is very important. “Other things being equal, the greater the contextual effects, the greater the relevance." (Sperber & Wilson, 1986:119) Besides that, domestication and foreignization complement each other and play a part together in cultural translation. The thesis is divided into five chapters. Chapter I introduces the background and objectives of the study. Chapter II reviews relevant literature concerning cultural default and relevance theory. Chapter III analyzes the collected eleven data. Chapter IV discusses the findings of the research. Chapter V summarizes the main points and points out limitations of the study. Keywords: cultural default; relevance theory; optimal relevance; domestication; foreignization