Detective Chinatown 1900 is a 2025 Chinese comedy mystery buddy film directed by Chen Sicheng and Dai Mo, starring Wang Baoqiang, Liu Haoran, with a special appearance by Chow Yun-fat. It is the fourth installment in the Detective Chinatown franchise. It is not narratively connected to the previous installments in the franchise. Wang Baoqiang and Liu Haoran, the leads in the previous films, returned but play different characters. The film, which is set in San Francisco in 1900, follows the story of Qin Fu and Ah Gui's investigation into the murder of a white woman in Chinatown. Principal photography began in July 2024 at Laoling Film Studio and ended in October of the same year. The film premiered on 29 January 2025 during the Spring Festival. The musical score for the film was composed by Nathan Wang.