Class inequalities have been one of the foci in sociology of education. This study explores educational effect of class in terms of junior high students' credeutial images.On the basis of a 15-rnonth research in an seven-grade class, with such methods as observation, interview, document analysis and questionnaire included, we find, first of all, students from middle classes believe 'there is no need to get to know anything about credentials, we have to study anyway;' while students of non middle-class origins say 'whatever, I may end up a senior high, if not a junior high graduate.' Secondly, middle-class students have faith that with credentials, they will be given some decent jobs as their dads; on the contrary their non-middle-class counterparts threaten themselves with the thought that without credentials, they may fail like their old men. Finally, rich students cam credentials to honor themselves whereas poor ones do this in glorification of their parents. Based on all these, we are convinced that there exist class-styled 'cognitive paths', on which classes exert their effects the most.