文章以韩礼德的系统功能语法为理论基础,以功能语法中人际功能的情态系统为支撑,从三个方面对马丁.路德.金著名的演讲《我有一个梦》进行统计分析:情态句、情态操作词及人称代词。结果发现情态成分的重复,营造了巨大的亲和力,从而在演讲者劝服听众的过程中起到了重大作用。 Based on Halliday’s system function grammar and the modality system of interpersonal function in functional grammar, the article makes statistical analysis on Martin Luther King’s famous speech “I Have a Dream” from three aspects: Modality Operational Pronoun and Personal Pronouns. As a result, it was found that the repetition of modality elements created great affinity and thus played a significant role in the speaker’s persuasion of the audience.