Wen'an is a county in the central part of Hebei province, China, on the upper reaches of the Daqing River (大清河), a tributary of the Hai River, and bordering Tianjin to the east. It is under the administration of the prefecture-level city of Langfang, and, as of 2004, had a population of 460,000 residing in an area of 980 km2 (380 sq mi).