系统功能语言学认为语言有三大元功能，即概念功能、人际功能和语篇功能。近年来，TED演讲则受到了大众的广泛关注和追捧。因此，有必要通过语言学研究来理解TED演讲受欢迎的原因及其中人际功能的表达方式。而系统功能语法为本研究提供了理论框架，以此作为基础分析自建语料库中表达人际功能的语言手段。研究结果显示，陈述句在语气的使用上占大多数，主要用来叙事或表达观点。在有关情态的分析中，演讲者多用低值或中值的情态动词，这样可以在号召大众环保的同时尽可能保证语言的礼貌、得体。除此之外，演讲者对于人称代词的使用也十分小心，在演讲时有技巧性地突出人与自然相互依存、和谐共处的生态理念。综上，本研究进一步拓宽了相关理论的应用领域，并为环保类语料提供了新的研究视角，对于演讲人士和环保宣传人士都有一定的指导意义。

According to Systemic Functional Grammar, the three metafunctions of language are respectively ideational, interpersonal and textual metafunctions. While TED speech has gained much attention and appreciation in recent years, it is necessary to understand the reason behind its popularity and the realization of interpersonal metafunctions. Systemic Functional Grammar is used as the theoretical framework for this study, which explores the linguistic devices used to realize the interpersonal metafunctions based on a self-built corpus. The results show that the declaratives account for the majority of mood structures to express statements and opinions. In terms of modality, low value or median value operators are frequently adopted to call for environmental protection in a polite and decent way. Besides, the speakers are very careful in the use of personal pronouns to convey the ecological idea of interdependent and harmonious relationship between man and nature. This study further broadens the application field of the theory and provides a new perspective of analyzing discourse on environmental protection, which has guiding significance for both public speakers and environmentalists.