In 1939, the Central Committee of the Chinese Communist Party decided to send a group of children of party revolutionaries to study in the Soviet Union. In November 1939 Liu and his sister Liu Aiqin arrived at the childrens home in Monino, where Mao Zedongs sons Mao Anying and Mao Anqing were also living. While in Soviet Union, Liu was known by Russian name Klim (Клим).
After one semester of study, Liu Yunbin moved to Interdom, which was 300 kilometers away from Moscow, at the city of Ivanovo, and was sponsored by the International Red Aid of the Soviet Union. During his time at the school, he studied very hard and in June 1941, following the start of the German invasion of the Soviet Union, Liu actively participated in the labors organized by the International Childrens Institute, such as land reclamation, logging, and moving firewood. He also took the initiative to donate blood for the Soviet Red Army soldiers fighting in the frontline. He was selected as one of the leaders of the International Childrens Institute student union, and soon joined the Komsomol and served as the head of the organization in the International Children's Academy.
After graduation from high school in 1945, Liu was admitted to the Moscow Iron and Steel Institute, where he majored in smelting. During his time in the institution, he also joined the Communist Party of the Soviet Union and after graduation, he was admitted to the Department of Chemistry at Moscow State University with honors and as a graduate student in radiochemistry. He graduated in 1955 with an associate doctorate degree and entered the Moscow University Institute of Chemistry as a senior researcher. In a 1955 letter to Liu Yunbin, Liu Shaoqi stated:
In 1957, he returned to China, where he resided in his father's residence in Zhongnanhai for a few days, before moving to Fangshan County, Shanxi, 50 kilometers away from Beijing, to work at the China Institute of Atomic Energy (Institute 401), which was one of the earliest nuclear weapons research institutes in China. He made outstanding contributions to nuclear energy research and was awarded the title of associate researcher.
In 1959, when Sino-Soviet relations deteriorated, the Soviet Union refused to provide China with technical materials required to develop the atomic bomb. In 1961, researchers from the First Institute of the China Institute of Atomic Energy were transferred to the China Nuclear Fuel Component Factory (Factory 202) at Baotou, Inner Mongolia Autonomous Region, where they set up a second laboratory, which was responsible for the research into thermonuclear materials.
In the winter of 1962, Liu Yunbin arrived at the 202 Factory, where he was appointed by his superiors as the director of the Second Research Office. The office under his leadership began research and organizational work for the atomic bomb project and, on 16 October 1964, China's first atomic bomb was successfully detonated at the Lop Nur test site, which resulted in China becoming the fifth nuclear power in the world and the first Asian nation to possess nuclear capability.