The Battle at Lake Changjin (Chinese: 长津湖) is a 2021 Chinese war drama film co-produced and co-directed by Chen Kaige, Tsui Hark and Dante Lam, written by Lan Xiaolong and Huang Jianxin, and starring Wu Jing and Jackson Yee. It was commissioned by the Central Propaganda Department of the Chinese Communist Party as part of the Party's 100th anniversary celebrations. The film depicts the story of the North Korea-allied Chinese People's Volunteer Army, forcing U.S. forces to withdraw in a fictionalized retelling of the Battle of the Chosin Reservoir during the Korean War.

The Battle at Lake Changjin is the most expensive film ever produced in China, with a budget of $200 million. The film grossed $913 million at the worldwide box office, making it the second-highest-grossing film of 2021, the highest-grossing Chinese film of all time, the highest-grossing non-English film, and the second highest-grossing film in a single market. A sequel to the film, The Battle at Lake Changjin II, was released on 1 February 2022.

The film's depiction of the battle has been described as containing historical inaccuracies and has garnered controversy in some countries, including South Korea. The film has also been described as propaganda.