So far, most stylisticians of drama seem to have excluded stage directions from their studies.Even when stage directions came into the horizon of dramatic stylisticians, they were only considered as indicators of the complicated writer-reader relationship.The exclusion of stage directions as an object for stylistic study is probably caused by the fact that these scholars consider the dialogue as the dramatic language proper and stage directions as acts or performance, which is beyond the study of language.This paper, however, will argue that stage directions are an important component of the dramatic text, therefore should be included in stylistics of drama.Moreover, it will argue that stage directions do not just reveal the writer-reader relationship, but also contributes to the aesthetic values of drama.This paper will first discuss some theoretical preliminaries relevant to this argument, then show by deletion test and substitution test that stage directions are indispensable for drama interpretation.