Changchun (literally "Long Spring") is the capital and largest city of Jilin province, located in the northeast of the People's Republic of China, in the center of the Songliao Plain. It is a sub-provincial city. The name originated from the Jurchen language. As of 2007, Changchun has a population of 7.46 million, including counties and county-level cities. The urban districts have a total population of 3.58 million.

Changchun started as a minor trading town. In 1800, Emperor Jiaqing of the Qing Dynasty selected a small village on the east bank of the Yitong River and named it "Changchun Ting." In 1889, it was promoted as "Changchun Fu".

It expanded rapidly as the junction between of the Japanese-owned South Manchurian Railway and the Russian-owned Chinese Eastern Railway which had different rail gauges, as well as permit licences, from 1905-1935. Changchun had railway repair shops and branch lines originating in Changchun extended into Korea and Inner Mongolia. In 1932 moving from Jilin City (Kirin city) 200 km to the east, Changchun became the capital of Manchukuo, a state in Manchuria. Then known as Hsinking, the capital was a well-planned city with broad avenues and modern public works. The city underwent rapid expansion in both its economy and infrastructures.

From 1931 to 1945 China's last emperor Pu Yi was installed as the Manchukuo government head by the Japanese authority. He resided in the Imperial Palace which is now the Museum of the Manchu State Imperial Palace.

During the Second Sino-Japanese War (1937–1945) and World War II the Imperial Japanese Army implemented in Changchun the headquarters of Unit 100 ("Wakamatsu Unit"), under command of veterinarian Yujiro Wakamatsu. This facility dedicated itself to both the study of animal vaccines to protect Japanese resources, and, especially, veterinary biological-warfare. Diseases were tested for use against the Soviet and Chinese horses and other livestock. In addition to these tests, Unit 100 ran a bacteria factory to produce the pathogens needed by other units. Biological sabotage testing was also handled at this facility: everything from poisons to chemical crop destruction.

Severely damaged during World War II, the city was liberated by the Soviet Red Army in 1945. The Russians maintained a presence in the city after the Chinese civil war until 1946. Kuomintang forces occupied the city in 1946, but were unable to hold the countryside against Chinese Communist forces. The city fell to the communists in 1948 after a 12-month-long siege by the People's Liberation Army that resulted in a massive famine with a civilian death toll of 100,000 to 300,000. Renamed Changchun by the People's Republic of China government, it became the capital of Jilin in 1954.

The Changchun Film Studio is also one of the remaining film factories of the era. From the 1950s, it was designated to become a center for China's automotive industry. The famous Red Flag limousines were made in Changchun as were the Liberation (Jiefang) trucks based on a Ford model used in Russia who supplied much of the early manufacturing machinery.

Changchun hosted the 2007 Winter Asian Games.