After World War II, the Chinese Civil War and the Indochina War broke out one after another. The Chinese Communist Party (CCP) and the League for the Independence of Vietnam (Viet Minh) launched cross-border military cooperation, challenging the legitimacy of the Kuomintang (KMT) in China and the French colonial regime in Indochina, and bringing together the socialist revolutionary cause of China and the anti-colonial movement of the people of Southeast Asia. At that time, the cooperation was mainly divided into three categories: First, when the guerrillas of the CCP in the southern border of China were forced to transfer to Vietnamese territory for concealment and training, the Viet Minh provided accommodation as well as financial and material support. Second, while they were in Vietnam, the CCP members assisted the Viet Minh in carrying out daily logistics, intelligence, and publicity work to help the Vietnamese army in training and in organizing the self-defence forces of the overseas Chinese. Third, starting from 1948, the CCP and the Viet Minh army carried out joint military operations on their border. Overall, the exchanges and cooperation between China and Vietnam from 1945 and 1947 were spontaneous, small-scale, scattered, and secretive. However, with the transformation of the Civil War in China in 1948, the exchanges and cooperation between the two sides took a strategic and long-term perspective. The Vietnamese first sent troops to help the Chinese side liberate the border areas, and then waited for the Chinese People’s Liberation Army (PLA) to move to the south to help the Vietnamese resistance, laying the groundwork for an anti-France campaign after the founding of the People’s Republic of China (PRC). At that time, the two parties of China and Vietnam were equal and mutually supportive, and the CCP’s leadership over the Viet Minh after its successful revolution was not yet formed. In short, the mutual assistance during the revolution between China and Vietnam advanced the process of the revolutionary war in the two countries, reconstructed the relations between the two parties and two countries, and had a far-reaching impact on the revolutionary situation in Southeast Asia and the development of the Asian socialist camp.