嫩江（满语： Non ula）是松花江最大支流。位于中国黑龙江省西部，部分河段为黑龙江省与内蒙古自治区边界。源出大兴安岭北麓伊勒呼里山，南流到镇赉县，经吉林省大安市在三岔河汇入松花江。长1370千米，流域面积28.3万平方千米。支流主要有甘河、讷谟尔河、诺敏河、绰尔河、洮儿河等。

无论从长度、流量还是流域面积看，嫩江都实应为松花江正源，只因第二松花江发源于长白山天池而在中国清代被奉为松花江的正源，故正源之说延续至今。

嫩江有4个月冰期，江轮可航至齐齐哈尔。嫩江流经坡度很缓的松嫩平原，有许多湖泊、沼泽。

The Nen River or Nenjiang (Chinese:嫩江; pinyin:Nèn Jiāng; Wade–Giles:Nen-chiang), or Nonni (Manchu:ᠨᠣᠨ
ᡠᠯᠠ;Möllendorff: Non ula;Abkai: Non ula) is a river in Northeast China. The Nen River flows through the northern part of Heilongjiang Province and the northeastern section of Inner Mongolia, some parts of the river forming the border between the two regions. At 1370 kilometres (850 mi) in length, the Nen River is the longest tributary of the Songhua River.