Dandong lies in the southeast of Liaoning Province, separated from the North Korea by the exotic Yalu River. The Yellow Sea is off its south edge and the modern city Dalian is just adjacent to the city in the northeast.

Situated in China's frontier area, Dandong has always been a vital fortress of great military importance since extremely long ago. During the last years of the Ming Dynasty (1368-1644), the cutting-off of trade communication with outside areas made it decay, and it was gradually involved in a promising state in early Qing Dynasty (1644-1911). It was until 1965 that Dandong was changed its name from Andong City.

Except the coastal plain, majority of the city's territory is seated in the vast mountainous and hilly area in eastern Liaoning. Medium and low mountains in the north, hilly area in the south and the coastal plain in south fringes of Dandong constitute the main components of the city's landform.