Changyŏn is bordered to the north by Kwail and Songhwa, to the east by Samch'ŏn and T'aet'an, to the south by Ryongyŏn, and to the west by the Yellow Sea.

Most of the land in Changyŏn is composed of flat plains, with mountains forming its borders.

[2] Changyŏn county was created under the Yi dynasty.

Chaeryŏng was briefly merged into the newly formed Hwanghae District in 1895 during an experimental redistricting, but was restored to its previous form in 1896.

The county is divided into one town (ŭp), 1 Worker's District (rodongjagu) and 19 villages (ri).