Based on Conceptual Metaphor Theory, this study compares and contrasts the metaphorical extensions of the spatial dimensional adjectives Da in Chinese and Big in English. By investigating their dictionary meanings, the study finds, first, that the spatial concepts Big and Da can be mapped into such common abstract domains as TIME, QUANTITY, SCALE, SOCIAL HIERARCHY and others. Second, Da is richer in semantic mappings to source domains like AGE, EVALUATION, SENSES and WEATHER, while Big is related to IMPORTANCE and FORCE. However, the metaphorical scope of Da is wider than that of its English counterpart Big and thus its semantic capacity is also bigger. Third, the universals of the metaphorical extension of Da and Big result from the similar space that English and Chinese people live in and their similar embodied experience while the differences can be attributed to the characteristics of their national thought, culture and language typology.