The inauguration of the People's Republic, known in Chinese as Kaiguo dadian (开国大典), by Mao Zedong on Saturday 1 October 1949, the Gate of Heavenly Peace (Tiananmen Gate) in Beijing. Pictured are, from left to right: Lin Boqu, Zhou Enlai, Dong Biwu (almost invisible), Zhu De, Liu Shaoqi, Chen Shutong (probably), Song Qingling, Guo Moruo, Li Jishen, Zhang Lan, Mao Zedong. In this version of the painting, Gao Gang, who had been purged from the Party, was replaced by a potted chrysanthemum. For more information, see the page on Dong Xiwen. 
This is a print from the 22nd edition (October 1953).

Sources:

Julia F. Andrews, Painters and Politics in the People's Republic of China, 1949-1979 (Berkeley, etc.: University of California Press, 1994)

Chang-tai Hung, "Oil Paintings and Politics: Weaving a Heroic Tale of the Chinese Communist Revolution", Comparative Studies in Society and History, vol. 49, no. 4 (2007), pp. 783-814