Abstract: By analyzing the language used in the American humorous series Friends, this article intends to explore gender differences in speech manner from the perspective of interpersonal metafunction. The research finds out that females tend to be more polite than man in expressing the interpersonal metafunction by preferring to use interrogative mood, tag questions, modal verbs and speech hedges, which facilitate to soften the language they utter in order to make the speech more euphemistical. The result shows that women are more diffident than men in undertaking language to express the interpersonal metafunction to establish and maintain their relationship with others，which may mirror the different social statuses the two genders enjoyed.