The Collocation restriction of degree adverbs has been a difficult part in teaching Chinese as second language. This paper explores the semantic, syntactic and pragmatic properties of degree adverbs from a cognitive perspective. These properties pertain to degree structure, subjectivity and mood. If we accept the assumption that degree adverbs contain semantic categories, three types of errors, which are observed by Chen and Li (1997), Tong (1998), Xu (1998) and Hu (2005), might be explained under a unified and reasonable account.