EST (English for science and technology) translation plays an increasingly significant role in scientific field. Compared with the general Non-tech English style, EST has its own typical features which were intensively represented by the extensive use of long sentences, as they contain enormous amount of information and complex structures, and there are great differences in sentence patterns between English and Chinese. Through case studies, this paper explores the emerging “Functional Equivalence” Cases in E-C Translation of Long Sentences in EST by analyzing the text hypotaxis-prominent English sentences, which is proved to be compact in structure whereas parataxis-prominent Chinese sentences are loose in structure. The paper induces that as one of the information type texts, EST’s effect to reader is more univocal than other texts for it aims to convey information to reader and requires high accuracy. The paper also described the functional equivalence theoruy's implications for applied translation teaching by arguing that Functional equivalence theory lays emphasize on target reader’s response and it is more suitable to translate EST under the guidance of functional equivalence theory.