The Bằng River (Vietnamese: Sông Bằng) is a river of Cao Bằng, Vietnam.[1] It flows for 108 kilometres.
It originates in the Guangxi, China, flows in the northwest - southeast to Cao Bằng through Sóc Giang border gate, Sóc Hà rural commune, Hà Quảng.
From Sóc Giang rural commune, it flows in the southeast through Hà Quảng, Hòa An, Cao Bằng, Phục Hòa. The river flowing through Cao Bằng ends at Tà Lùng border gate, Mỹ Hưng rural commune, Phục Hòa (at the southeast of Cao Bằng) before it returns to Guangxi, China.
It's confluence with the Kỳ Cùng River near Longzhou, Guangxi to form Zuo River, a tributaries to the south of Yu River.