This thesis aims to examine the grammatical characteristics and meanings of `□` co nstruction in Middle Korean and Pre-modern Korean. And I discuss the historical change of `□` construction systematically. The basic meaning of `□` is similarity and it is related to comparison and epistemic modality. On the basis of distribution, I deal with the various characteristics of `□` in comparative, epistemic modal and other construction. `□` construction has the lexical meaning, similarity obviously in repetition construction and combining demonstrative verbs. `ㄴ/ㄹ □ □다` has the epistemic modal meaning and it is concerned with the quotation of speaker`s thought. `□ 식브다`, `-ㄴ/ㄹ □이` has the epistemic modal meaning newly and `□` construction combines idiomatic phrases and demonstrative verbs productively in Pre-modern Korean.