Taishan is a county-level city in the southwest of Guangdong province, China. It is administered as part of the prefecture-level city of Jiangmen. During the 2020 census, there were 907,354 inhabitants (941,095 in 2010), but only 433,266 were considered urban. Taishan calls itself the "First Home of the Overseas Chinese". An estimated half a million Chinese Americans are of Taishanese descent.

It was named Xinning (新宁) until 1914, which was romanised as "Sunning".

Taishan is in the Pearl River Delta, in southwestern Jiangmen Prefecture. It has 95 islands and islets, including Shangchuan Island, Guangdong's largest island now that Hainan is a separate province. Taishan is one of Guangdong's "Four Counties" (Sze Yup), which excluded Heshan and is now part of the Greater Taishan Region.

During the Ming dynasty, the area of present-day Taishan was carved out of Xinhui County on 12 February 1499 as "Xinning County". By the 19th century, Xinning was already a source of migrant and emigrant workers, but a series of subsequent natural and political disasters in the area exacerbated the situation. Aside from the disruption of the Sea Ban regulations (Haijin) themselves, their revocation led to an influx of northern settlers who began long-running feuds with the returning locals; this erupted into full-scale war in the 1850s and '60s. The 1842 Treaty of Nanking that ended the First Opium War opened China to greater foreign trade just before the California Gold Rush made the prospect of emigration to the United States appealing. Many also served as contract workers abroad, as in Hawaii, Peru and Cuba and—most famously—for the Central Pacific half of America's Transcontinental Railroad, where the Chinese made up 80% of the company's workforce as they laid track over the mountains and deserts of the west. By 1870, there were 63,000 Chinese in the U.S., almost all in California.

Chin Gee Hee's Sun Ning Railway Company connected Sun Ning (Xinning) with its hinterland in 1908 and reached Jiangmen (Kongmoon) in 1913. It was notable as one of only three railways financed, built, owned, and run by the Chinese themselves before the 1949 Communist victory in the Chinese Civil War.

In 1914, the new Republican government renamed the area Taishan County to avoid confusion with other places named Xinning. (Foreign sources now frequently confuse it with Mount Tai in Shandong.) During the Second World War, the Sun Ning Railway was destroyed to prevent its use by the Japanese. Japanese soldiers entered Taicheng, the county seat, in March 1941 and killed nearly 280 people. One quarter of the "Flying Tigers", a joint American and Chinese group of airmen who fought the Japanese before the U.S. entered the Second World War, hailed from Taishan.

Taishan was promoted to county-level city status on 17 April 1992, reflecting its increasing level of urbanization.

Taishan administers one subdistrict and 16 towns, which in turn are subdivided into 313 administrative villages (村委会), and residential communities (社区委会). The city has 3,655 natural villages, but they do not function as administrative divisions (自然村).