In the 1960s, Liu and his colleagues were tasked with recycling nuclear fuels from China's nuclear reactors. He worked under primitive conditions and was exposed to radiation for more than a decade, which caused his hair to turn gray before he was 40.
Starting in 1974, Liu focused on the application of nuclear science in medical fields and the research and development of radiopharmaceuticals. He became a professor at Beijing Normal University and served as deputy chair of its chemistry department and director of its Institute of Applied Chemistry. He made important discoveries in the properties of technetium-99m (99mTc), a radioactive isotope of technetium, and developed several medicines using 99mTc. He also researched radioactive isotopes of halogens, including bromine-82, iodine-131, and astatine-211.
Liu's research won many awards, including the National Science and Technology Conference Award (1979), the State Education Commission Science and Technology Progress Award, Second Class (1993 and 1998), and the State Science and Technology Progress Award, Second Class (1999). He was elected as an academician of the Chinese Academy of Engineering in 1997.