English teaching is an integral part of education,which shoulders the responsibility of rendering rudimentary knowledge of English to the students,providing the students with the listening,speaking,reading and writing ability,as well as the obligation of carrying out ideological education and cultivating their noble and healthy sentiment.In teaching,the teachers should pay special attention to the students' thirst for English learning and give full play to their initiative,which demands enough lead-in preparation before class.The lead-in of new lessons bears a direct impact on the quality of the classroom teaching.This thesis will make an analysis of this problem in two aspects.