"Yi-Shi Duan (1927-2016) was one of the world-renowned pioneers in the study of gauge field theory and general relativity in China. Trained in former Soviet Union, Prof. Duan returned to China in 1957 to work in Lanzhou University for 60 years. In 1963, he came up with a general co-variant form of conservation law of energy-momentum tensor in general relativity. In 1979, he suggested that the gauge potential could be decomposed, which has importance implications to gauge field theory. He trained a big team of talents in theoretical physics in China. His contributions to theoretical physics in China have earned him praise from both Professor S S Chern and Professor C N Yang"--