Hải Dðáng () was a city in Vietnam. It was the capital of Hải Dðáng, an industrialized province in the Hanoi Capital Region and the Red River Delta in Northern Vietnam, now merged into Haiphong. The city is at the midpoint between the capital Hanoi and the major port Haiphong, and is part of the Northern Key Economic Zone. In 2019, Hai Duong city had a population of 241,373.
The name first appeared officially in 1498. In feudal times, Hải Dðáng indicated a vast area from east of Hanoi to the sea of Hai Phong nowadays. This area corresponds to all of modern Hải Dðáng, Haiphong, most of Hðng Yên and the southwestern corner of Quảng Ninh. Hải Dðáng city is in the middle of this historical area and was the location of a citadel defending the capital. Because of this historical location, Thành ÃÂông (eastern citadel) is a common nickname of Hải Dðáng. The name "Hải Dðáng" () comes from Sino-Vietnamese and means "ocean sun" in English.
Hải Dðáng city is bordered to the north-east by Nam Sách and Thanh Hàdistricts, to the west by Cẩm Giàng District, and to the south by Gia Lá»Âc and Tứ Kỳ districts, and also a branch of the Sat River. A branch of the Cái River (literally, "mother river" in Vietnamese) divides the city into two parts, on one side the urban area, and on the other side rural and industrial outskirts. The city is located in the centre of both the Northern Economic Area and of the HanoiâÂÂHaiphongâÂÂQuảng Ninh development region as well. Hải Dðáng is located from Hanoi, from Haiphong, and from Halong Bay. A railway, National Highway No.5 (Hanoi - Hải Dðáng - Haiphong) and National Highway No.18 (Bắc Ninh - Hải Dðáng - Quảng Ninh) all pass through the province. Hải Dðáng Province is also located within the Red River Delta of northern Vietnam. It is bordered by Haiphong and Quảng Ninh provinces in the east, Hðng Yên in the west, Bắc Ninh and Bắc Giang in the north, and Thái Bình in the south. With a total area of , Hải Dðáng Province has one major city (Hải Dðáng) and eleven districts (Bình Giang, Cẩm Giàng, ChàLinh, Gia Lá»Âc, Kim Thành, Kinh Môn, Nam Sách, Ninh Giang, Thanh HÃÂ, Thanh Miá»Ân and Tứ Kỳ).
Nowadays, highways make it easier to commute between Haiphong, Hải Dðáng and Hanoi. As of October 2017 it takes between 45 minutes and one hour to travel from Hải Dðáng to Hanoi.
Hải Dðáng city was built in 1804, and was first called "Thành ÃÂông" (Sino-Vietnamese for eastern citadel), referring to the citadel east of Vietnam's capital, Hanoi. During the French colonial period, Hải Dðáng was a town. Before 1968, Hải Dðáng was a town in Hải Dðáng Province. Between 1968 and 1996 it was the capital of Hải Hðng Province after the provinces of Hải Dðáng and Hðng Yên merged to form Hải Hðng. On November 6, 1996, following the separation of Hải Dðáng and Hðng Yên provinces, Hải Dðáng became the capital of Hải Dðáng province. On August 6, 1997, Hải Dðáng was established as a city.
From 2019, Hải Dðáng city contains 20 wards (urban) and 7 communes (rural).
In April 2025, the Central Committee of the Communist Party of Vietnam adopted Resolution No. 60-NQ/TW at its 11th Plenum of the 13th tenure, approving the merger of Hai Duong province and Hai Phong city into a single administrative unit.
Following this, the Standing Committee of the National Assembly issued Resolution No. 1669/NQ-UBTVQH15, which provided detailed arrangements for the consolidation of commune- and ward-level administrative units in Hai Duong and Hai Phong.
On 1 December 2025, Hai Duong City was officially reorganized with 28 newly consolidated communes, wards, and townships commencing operations. The handover of seals and personnel appointments took place at the Hai Duong Provincial Public Administration Service Center. The reorganization was intended to streamline the administrative apparatus, improve governance efficiency, and support socio-economic development in the region.
Hai Duong city has a quite convenient waterway transportation system. From Hai Duong city, according to the Thai Binh river system, boats can go down to Hai Phong Port, or back to the northern midland mountainous provinces.
Cong Cau Port is an inland waterway port with the function of loading and unloading goods - mainly raw materials - to and from other provinces and cities, the port has a capacity of 300,000 tons/year and a system of wharves and yards to meet the needs of domestic and foreign tourists. Transport goods by water in a convenient way.
The Hanoi-Hai Phong railway passes through Hai Duong city about 13 km, starting from Viet Hoa ward and ending at Ai Quoc ward. Connecting with other provinces at Hai Duong Station- the railway hub of the whole province, and Tien Trung is the transit station of the Northeast region of the province.
On Vietnam's Provincial Competitiveness Index 2023, a key tool for evaluating the business environment in Vietnam's provinces, Hai Duong received a score of 68.68. This was an improvement from 2022 in which the province received a score of 65.22. In 2023, the province received its highest scores on the âÂÂEntry Costs' and 'Law and Order' criterion and lowest scores on 'Transparency' and 'Business Support Policy'.