The purpose of this study is to find the syntactic rules in adverbial clauses in 17·18th century`s Korean. This study is based on the paper of adverbial clauses in 15, 16th century`s Korean. This paper can be summarized as follows: The basic structure of the `nd-gi-da(너기다)` adverbial clause is `A가 B를 [adverbial clause} nagida`. The object(B를) is transformed from subject in a adverbial clause. The predicate in the `na-gi-da(너기다)` adverbial clause can be classified into `feeling adjective` and `judgment adjective`. When the feeling adjective is the predicate in the adverbial clause, adverbial clause. In `na-gi-da(너기다)` adverbial clause in 17·18th century`s Korean, `-ke` adverbial clauses are rarely found than `-I` adverbial clauses. Four illustrative sentences are found in 17th century and twenty seven illustrative sentences are found in 18th century`s Korean. The predicates in the adverbial clause appeared from 18th century`s, that is selected various words. Generally `-soi(소이)` was discussed as a adverbial derivational Suffix, but this paper consider it as adverbial endings. This is because it should suppose subject in a adverbial clause at deep structure, a syntactic function should be more valued than a form. In addition, It seems to make a quotative adverbial clause when it compared `-soi(소이)` and `-i(이)`. The predicates in the `na-gi-da(너기다)` adverbial clause appeared adjective in 15·16th century`s Korean, but appear rarely psychological verbs in 17·18th century`s Korean.