Abstract: Appraisal meaning of language is similar to subjective meaning, and is realized by lexical and grammatical means. According to “Complementarities of language system” put forward by Halliday, morpheme is on the lexico-grammatical continuity and is among the means to realize the appraisal meaning of language. Linguistic system and instance are two complementary perspectives, studies on which may adopt a system-instance direction or the opposite one. This paper takes the starting point of meaning potential and probes step by step to the 125 instances via an instantiation dimension by adopting inductive method and drawing data from the “Appraisal Corpus”. The findings highlights the following points: instantiation process type of English morpheme differs according to text instance and text type, among which five major types are identified; besides, three key factors governing the instantiation process are: context type, semantic category and semantic orientation. In addition, the findings might offer a new perspective to view the agnate relations among different text types in the sense of stylistics.