In this paper,we use syntax as the start point to proclaim the properties and structural position of adverb adjuncts. First of all,we divided the adjunct into two part: functional category adjunct and lexical category adjunct,then reveal the features and the syntactic position and the generative process of the adjunct from the point of syntax. In this paper,we propose and analyze two kinds of special adjuncts called ext- CP adjunct and inner- V adjunct according to the syntax properties of adverb adjuncts and the relationship between adjuncts and XP. We also make further analysis about the subject- oriented adjunct.