Jacobson first discusses the position and function of poetics in literary research from the difference between literary language and daily life language. Everyday language is only to satisfy people's daily communication. It only promotes communication between the two sides. The language it uses is organized into language units according to the usual word formation, grammar and rhetoric methods, and its purpose is to make people easy to understand and communicate. Literary language is often the processing, distortion and deformation of everyday language, in order to achieve the effect of defamiliarization and highlight the characteristics of literary language itself, that is, configuration, combination and processing. It aims at itself and shows the value and significance of language itself. Jacobson said in his book What is Poetry: "Where is the poetic expression? The performance is that words make people feel words, not just the expression of the referred object or the emotional attack. The expression in words, word order, meaning and its external and internal forms is not only an inseparable realistic basis, but also has its own weight and significance. " Here, by discussing the poetic expression in poetry, Jacobson extended his attention to the formal skills of poetics. Furthermore, in Jacobson's view, studying poetics is to study the composition of various formal elements in poetics, so as to achieve the purpose of scientific research on poetics. On the basis of distinguishing daily language from literary language, Jacobson further discusses six factors of daily language and their corresponding six functions: speaker, receiver, context, information, contact and code and their corresponding expressive function, conative function, referential function, poetic function, communicative function and metalinguistic function. In daily language communication activities, both parties should realize normal and successful communication activities in contact with each other according to a certain context and with language code as the medium. It can be seen from this that literary language is only a function of language communication, and it pays more attention to the information function of language. Studying the poetic function of literary language to convey information can make the essence of language more exposed, thus making people pay more attention to the characteristics of language itself, while other functions of language, such as metalinguistic function and communicative function, are relatively less important.
Jacobson attaches great importance to metaphor and metonymy, two basic rhetorical methods, from the perspective of studying the poetic function of language. Metaphor and metonymy were originally just two basic rhetorical methods, but Jacobson endowed them with deeper universal meaning and regarded them as the basic mode of poetry analysis. Jacobson believes that people's choice of language symbols has the characteristics of similarity and metaphor; It has the characteristics of adjacency and metonymy in the process of language symbol combination. Because people's choice of language symbols has a diachronic dimension, metaphor and metonymy are of great significance for understanding the author's diachronic choice and combination of language symbols in poetic language. Jacobson further pointed out that there are more metaphors than metonymy in poetry and metonymy in prose. The principle of similarity is dominant in poetry, whether in meter, rhythm, rhyme, etc. Proximity principle is dominant in prose, and metonymy plays a great role in it.
Jacobson also attaches great importance to the study of grammatical structure and function in Poetics. He thinks that poets can't help but pay attention to grammatical rules in their creation. Grammatical rules often have mandatory characteristics, and grammatical structure even plays an inherent supporting and leading role in every poem.