This chapter reviews China’s diplomacy during the Mao era from 1949 to 1978. The official line of China’s foreign policy during this period was not consistent but oscillated between a Maoist doctrine focusing on achieving world revolution and Zhou Enlai’s emphasis on peaceful coexistence among states of different ideologies. It is then argued that China’s diplomacy had been significantly subject to ideological considerations during this period. China engaged in a war on the Korean peninsula despite economic and human costs, disputed with both the US and the Soviet Union for ideological reasons, and isolated itself from the rest of the world at the height of the Cultural Revolution. It was not until in the early 1970s when an existential threat from the Soviet Union prompted China into a strategic recalibration and convergence with the US, and it was only after Mao Zedong’s death in 1976 that Deng Xiaoping could initiate a more pragmatic approach to China’s diplomacy.