Teaching style is the comprehensive expression of teachers’ideological realm,aesthetic ide-al,artistic culture and personality characteristics,and it is an important symbol of teachers’profes-sional development.The research chose six middle school teachers in Dalian as the subjects to investi-gate their teaching styles.It finds that middle school teachers’teaching style tends to be legislative, liberal and local.The teaching style is influenced by gender,lelve of students,subjects,education, teachers’profesional title and teaching age.Among the factors,teachers’professional title and teach-ing age are the major ones.The formation of teaching style follows certain underlying principles,and turns more stable with the increase of age.In addition,the teaching style is ususally formed at a crti-cal stage,so teachers should seize the criticial stage in forming their proper teaching style.