Haimen District (Haimen City), subordinate to Nantong City, Jiangsu Province, is located in the southeast of Jiangsu Province, on the north bank of the Yangtze River, bordering the Yellow Sea in the northeast, the Yangtze River in the south, Chongming District, Shanghai in the southeast, Qidong City in the east, Tongzhou District and Chongchuan District of Nantong City in the west and north, and facing Shanghai across the river, with a total area of 1148.71 square kilometers. As of June 2020, Haimen District has 3 streets and 9 towns under its jurisdiction. By 2021, Haimen District has a registered residence population of 982700 and a permanent population of 993000. Haimen District People's Government is located at No. 600, Beijing Middle Road, Haimen Street.

In the fifth year of the late Zhou Xiande (958), Haimen County was set up, which was under the jurisdiction of Tongzhou. In 2020, Haimen City will be abolished and Haimen District will be established. There are two kinds of dialects in Haimen, one is Haimen dialect, which belongs to Sandi dialect, and the other is Sijia dialect, which belongs to Tongdong dialect, both belong to the Taihu area of Wu dialect. The territory is flat with crisscross ditches and rivers. It belongs to the north subtropical monsoon climate zone with four distinct seasons.

Haimen District is a national model county for double support, a national demonstration area for ecological civilization construction, a national health city, an advantageous area for agricultural products with Chinese characteristics, a sub-county for the protection and utilization of revolutionary cultural relics, and a national intellectual property demonstration city.

In 2021, the gross regional product of Haimen District will be 156.933 billion yuan, an increase of 9.4% over the previous year. Among them, the added value of the primary industry is 7.264 billion yuan, and the added value of the secondary industry is 76.969 billion yuan; The added value of the tertiary industry is 72.70 billion yuan, and the tertiary industrial structure is 4.6:49.1:46.3.