Abstract: Formulaic sequences refer to the daily idiomatic expressions and various kinds of oral and written utterances having a certain fixed syntactic and structural organization. Owing to its integrity and easily processed feature, it is not only the important means to realize the ideational meaning, but also the primary potential to realize the negotiable meaning. From the perspective of textual semantics, negotiable meaning is realized through negotiable system, which is realized through the system of speech functions, which is, in turn, realized through mood system, and which is, finally, realized through formulaic sequences and non-formulaic sequences. Then, what kinds of structures do formulaic sequences have to realize speech functions? Up to now, no research has been conducted concerning this issue. Therefore, with systemic-functional linguistics as the theoretical starting-point, corpus-based approach as the method and the script of the sitcom Friends as data, the present article intends to finger out the answer to the above question. The finding indicates that different formulaic sequences possessing certain structures respectively exchange information and goods-and-services, which thus not only realizes the speech function, but also fulfills the negotiation of meaning.