Lower Yangtze Mandarin (traditional Chinese: 下江官話; simplified Chinese: 下江官话; pinyin: Xiàjiāng Guānhuà) is one of the most divergent and least mutually-intelligible of the Mandarin language varieties, as it neighbours the Wu, Hui, and Gan groups of Sinitic languages. It is also known as Jiang–Huai Mandarin (traditional Chinese: 江淮官話; simplified Chinese: 江淮官话; pinyin: Jiānghuái Guānhuà), named after the Yangtze (Jiang) and Huai Rivers. Lower Yangtze is distinguished from most other Mandarin varieties by the retention of a final glottal stop in words that ended in a stop consonant in Middle Chinese.

During the Ming dynasty and early Qing dynasty, the lingua franca of administration was based on Lower Yangtze Mandarin. In the 19th century the base shifted to the Beijing dialect.

Lower Yangtze Mandarin is spoken in central Anhui, eastern Hubei, most of Jiangsu north of the Yangtze, as well as the area around Nanjing. The number of speakers was estimated in 1987 at 67 million.

The Language Atlas of China divides Lower Yangtze Mandarin into three branches:

There are also small islands of Jianghuai Mandarin (軍家話, Jūnjiāhuà) throughout Guangdong, Guangxi, Hainan and Fujian provinces, brought to these areas during the Ming dynasty by soldiers from Jiangsu, Anhui and Henan during the reign of Hongwu Emperor.

The Huizhou dialects, spoken in southern Anhui, share different features with Wu, Gan and Lower Yangtze Mandarin, making them difficult to classify. Earlier scholars had assigned to them one or other of those groups or to a top-level group of their own. The Atlas adopted the latter position, but it remains controversial.

The relationship of the Lower Yangtze Mandarin varieties to other varieties of Chinese has been an ongoing subject of debate. One quantitative study from the late 20th century by linguist Chin-Chuan Cheng focused on vocabulary lists, yielding the result that Eastern dialects of Jianghuai cluster with the Xiang and Gan varieties, whilst Northern and Southern Mandarin, despite being supposedly "genetically" related, were not in the original 35-word list. In the 100-word list they did cluster, albeit with other varieties.

Some Chinese linguists like Ting have claimed that Jianghuai is mostly Wu containing a superstratum of Mandarin; for example, the frequency and usage of the postposition 阿 as a postverbal aspect marker in the Taixing dialect of Jianghuai Mandarin can be seen as intermediate between Standard Mandarin, which tends to omit postverbal prepositions, and the Wu varieties, which tend towards omission of preverbal prepositions.