The language iconicity refers to the connection between the signifier and signified of the language symbol, and as an important theory of cognitive linguistics, it provides a new perspective and theoretical basis for English teaching. This paper interpreted some difficult phenomena to be explained in English grammar teaching by using distance iconicity, quantity iconicity and sequence iconicity, and analyze the example to probe the importance of iconicity in grammar teaching. The study shows that the syntax iconicity has a certain extent to reveal the relationship between the universal cognitive mechanism and the internal structure of the language, which is of great practical significance to English grammar teaching. So as to help teachers in the daily teaching, consciously guide students from the perspective of iconicity to understand and memorize grammar rules, reduce the burden of information processing and memory, and make up the lack of traditional grammar teaching.