It borders Kanggye and Changgang to the east, Manpo to the north and west, and Wiwon to the south.

The highest point is Sirubong in the south, at 1355 m above sea level.

The Changja River flows through north through the county, making a number of spectacular sharp twists on its way to join the Yalu.

Sijung is served by both road and rail, with the Manpo Line stopping in the county.

The Changja River reservoir is also used to ship some goods by water.