Abstract：Abstract：This paper comprehensively reviews related studies of expansion of the Predicator in Systemic Functional Grammar. By the study of transitivity and functional syntax, it aims to examine the category between the structure and verbal group complex. Based on functional meaning⁃focused principle, the results indicate that there are two types in expansion of the Predicator: structure with modal meaning and psychological adjectives as the core. When the verb “be” changes into functional word with showing interpersonal meaning through lexical combination, transitivity will follow second verb which realizes “aspect”, “voice” and is characterized by the prominent and prototypical event. And the corresponding syntactic structures are Auxiliary Verb and Auxiliary Extension. Furthermore, the central adjective in second type is main verb extension, which offers to realize the selection of mental process. In fact, quasi-expansions of the Predicator, centering modified adjectives and evaluative adjectives, are relational process. The following non-finite content is to cooperate or help completing meaning directly. In brief, all the four types are non-verbal-group complexes and single transitivity process. Key words: expansion of the Predicator; transitivity; verbal group complex; functional syntax; Systemic Functional Linguistics
