In modern spoken Chinese, we can often hear adverb postposition sentences. In this paper, we analyzed the causes and mechanisms of adverb postpositions by examining their pattern of usage . The phenomenon of adverb postposition in spoken Chinese follows a certain discourse mechanism based on several cognitive internal motivations. First, the relative urgency of speaking in oral dialogue allows the speaker to express more important information first and give less important information afterwards. This phenomenon often occurs in topic-comment sentences where the adverbs stay close to predicate focus. The postposition makes the focus more prominent. In argument-focus sentences, as the adverbs are semantically more closely related to subject arguments, they need to stay close to subject arguments and cannot be postdated. And when the speaker tells a new event to the listener, the adverbs in the sentence are generally in the periphery of the whole propositional information, it is not close to the subject or the predicate, so the postposition does not affect the conveyance of the meaning of the sentence. However, the subclass semantics of the adverbs still distinguish functional words and content words. Therefore, they are restricted by information structure in different ways. When the adverb acts as a focus or a part of focus areas, it cannot be left behind. When the adverb's meaning is functional and does not bear the propositional information of the sentence but only the modal information, it can easily stay out of the proposition and postposition.