Project 571 was the code name given to an alleged plot to execute a coup d'état against Chairman Mao Zedong in 1971 by the supporters of Lin Biao, then Vice Chairman of the Chinese Communist Party. In Chinese, the numbers "5-7-1" sound like the term 'armed uprising'. The Chinese Communist Party initially claimed that Lin Biao himself had devised Project 571, but evidence inside and outside of China has made it more likely that Lin's son, Lin Liguo, a high-ranking officer in the People's Liberation Army Air Force, instead developed the plot. Any plots that may have been planned or attempted by Lin Biao or his family ultimately failed. Lin's family attempted to flee China for the Soviet Union, but died when their plane crashed in Mongolia on September 13, 1971. A draft copy of the Project 571 outline was discovered following Lin's death, and was publicly circulated by the Chinese government as a means of explaining the event.

Lin Biao was a Chinese politician and Marshal of the People's Republic of China who was pivotal in the Communist victory during the Chinese Civil War, especially in Northeast China from 1946 to 1949. Lin was the general who commanded the decisive Liaoshen and Pingjin campaigns, in which he co-led the Manchurian Field Army to victory and led the People's Liberation Army into Beijing. He crossed the Yangtze River in 1949, decisively defeated the Kuomintang and took control of the coastal provinces in Southeast China. He ranked third among the Ten Marshals. Zhu De and Peng Dehuai were considered senior to Lin, and Lin ranked directly ahead of He Long and Liu Bocheng.