Existential construction is a common phenomenon in linguistics. This thesis is designed to make a comparative study of existential sentences in English and Chinese under the framework of Construction Grammar, trying to explore the nature of English and Chinese existential sentence. The major findings yielded in this study are summarized as follows: 1) the initial part in English existential sentence is a fixed there, which has a fixed form, fixed meaning and fixed position, and is only used as a subject, hut not a topic; while the initial part in Chinese existential sentence is a locative phrase or a temporal phrase which has a fixed position hut no fixed form and meaning, the initial part is both the subject and the topic. 2)vei,h is an essential factor in English existential sentence, hut not an essential factor in Chineseexistential sentence, in Chinese its occurrence is decided hy the context. Once verb occurs in construction, it will play a key role in construction and there will he interaction lietween verbs and construction.