What do they observe in China on December 25? July 9, 2020 by Pamela Landy In the Republic of China, Taiwan, they observe Constitution Day, a national holiday on December 25. Related Answers Who wrote “Mary Had a Little Lamb”? When did Labor Day become a national holiday in the U.S.? What is the earliest reference to Christmas’s being celebrated on December 25? Who was the last emperor of China? What song introduced each episode of “China Beach” (ABC, 1988-91)?