By comparing the representative cleft sentences in Chinese and Korean, this paper explores the cleft sentences of “shi......de”, the pseudo-cleft sentences of “...deshi...” and the cleft sentences of Korean “kes eun” corresponding relationship. Firstly, this paper studies the grammatical characteristics of “shi” and “de”, which are the constituent elements of Chinese cleft sentences, and their function of focus marking as focus constructions. Then, compare it with the Korean “kes eun” cleft sentence, and examine the similarities and differences of the two language cleft sentences. And then explore the relationship between the internal structure of focus constructions the two languages. Finally, the inner relationship between the two languages a t the grammatical level is explored to provide a theoretical basis for the realization of universal grammar.