Jiangyin (simplified Chinese: 江阴; traditional Chinese: 江陰; pinyin: Jiāngyīn; Wade–Giles: Chiangyin, Jiangyin dialect: [kɐ̞ŋ.jɪŋ]) is a county-level city on the southern bank of the Yangtze River. It is administered by the prefecture-level city of Wuxi, Jiangsu province. Jiangyin is an important transport hub on the Yangtze River and one of the most developed counties in China. It had 1,595,138 inhabitants in the 2010 census. The city is part of the Jiangyin-Zhangjiagang-Jingjiang metropolitan area, which has 3,526,260 inhabitants.

Jiangyin's name means "River Shade", from its location on the southern, shady bank of the Yangtze River.

Jiangyin has a long history. During the Spring and Autumn period and the Warring States period, it was part of the territory known as Yanling and served as the fiefdom of Ji Zha of Wu. Later, it became the estate of Lord Chunshen (Huang Xie) during the Warring States era. For these reasons, Jiangyin has historically been referred to as the "Ancient City of Yanling" (延陵古邑) and the "Old Domain of Chunshen" (春申旧封). Historical records indicate that Jiangyin has over 2,500 years of documented history. Jiangyin was initially a township of Yanling (延陵; later known as Piling, 毗陵) county. Since the township was located north of Ji Lake, it was given the name "Jiyang" (暨陽). In 281, it was promoted to a county of the Piling commandery. In 558, the northwestern part was separated from Lanling county (Wujin and its surrounding areas) to create Jiangyin county. It served as the seat of the Jiangyin commandery, with the same jurisdiction of the modern city, until the commandery was dissolved in 589. It was elevated to jun (military prefecture) status during the Southern Tang, until being restored as a county of Changzhou in 1071. It developed into an important port for overseas trade and a Maritime Trade Supervisory (市舶提擧司) was established to manage it in 1145. The county became a zhou (smaller prefecture) during the Yuan dynasty, but was reduced to county status again in 1367.

In 1472, a sandbank in the Yangtze River was made independent from Jiangyin county to establish Jingjiang county. In 1645, draconian enforcement of the decree ordering adoption of the Manchu style of hair and dress sparked resistance among the local Han Chinese. After the Qing ultimatum to "lose your hair or lose your head", they held the walled city against Qing sieges under a magistrate Yan Yingyuan(閻應元) 's leadership.

Following the Wuchang Uprising in 1911, the province of Jiangsu declared independence from the Qing dynasty. The new revolutionary government abolished the traditional administrative division of "prefectures" (府), and Jiangyin County became directly subordinate to the provincial authorities of Jiangsu Province.

In 1941, during the Second Sino-Japanese War, the Chinese Communist Party and its affiliated New Fourth Army established four county-level governments within and around the territory of Jiangyin: Jiangyin County, Chengdong County (also known as Yuxi), Chengxi County, and Shazhou County.

On April 22, 1949, Jiangyin came under the administration of the Changzhou Special District (常州专区) within the Southern Jiangsu Administrative Office [zh] (苏南行署) after the founding of the People's Republic of China. On February 6, 1953, it was transferred to the Suzhou Special District (苏州专区). In 1961 (officially approved on November 29, 1957 and implemented on December 1, 1961), nine communes in the northeastern part of Jiangyin County were reassigned to form the new Shazhou County (now Zhangjiagang City).

On January 18, 1983, Jiangsu Province implemented a "municipal-over-county" administrative system reform, under which Jiangyin County became administratively subordinate to the prefecture-level city of Wuxi.