Abstract
Krashen's theories of second language acquisition play a vital role in English teaching, in which "affective filter hypothesis" analyzes the influence of various affective factors on English learning. This paper focuses on Klashen's "affective filter hypothesis", analyzes the application of affective factors in the teaching practice of English grammar, and puts forward some teaching suggestions. The purpose of the study is to reduce the anxiety of the students in the second language grammar learning class, and then to find the most conducive state of English grammar learning, and to achieve the goal of English grammar teaching.