The Sino-Soviet Treaty of Friendship, Alliance and Mutual Assistance (Russian: Советско-китайский договор о дружбе, союзе и взаимной помощи, simplified Chinese: 中苏友好同盟互助条约; traditional Chinese: 中蘇友好同盟互助條約; pinyin: Zhōng-Sū Yǒuhǎo Tóngméng Hùzhù Tiáoyuē), or Sino-Soviet Treaty of Friendship and Alliance for short, was a bilateral treaty of alliance, collective security, aid and cooperation concluded between the People's Republic of China and the Union of Soviet Socialist Republics on February 14, 1950. It superseded the previous Sino-Soviet treaty signed by the Kuomintang government.

This treaty was signed against the background of the establishment of China's communist regime and the Cold War confrontation, resulting directly from Mao's foreign policy directive of "leaning to one side" (siding with the socialist camp) and Joseph Stalin's strategic and ideological considerations pertaining to the extension of Soviet influence in East Asia. Chairman of the Chinese Communist Party Mao Zedong travelled to the Soviet Union to sign the treaty, one of only two times in his life that he left China. The treaty laid the groundwork for Sino-Soviet cooperation and partnership. It provided China with security guarantees, and increased the scope for economic cooperation between the two countries. The treaty did not however, prevent relations between Beijing and Moscow from drastically deteriorating in the late 1950s to the early 1960s, during the Sino-Soviet split.

After the expiration of the treaty in 1979, Deng Xiaoping wanted China not to negotiate with the Soviets unless they agreed to China's demands such as withdrawing from Afghanistan, removing their troops from Mongolia and the Sino-Soviet border, and ceasing their support of the Vietnamese invasion of Cambodia. The expiration of the treaty allowed China to attack Vietnam, a Soviet ally, in the Third Indochina War as a response to Vietnam's invasion of Cambodia since the treaty had prevented China from attacking Soviet allies.