In the same year, as a second-year student, Yang passed the entrance examination and studied at National Southwestern Associated University.

He received a Bachelor of Science in 1942,[2] with his thesis on the application of group theory to molecular spectra, under the supervision of Ta-You Wu.

Yang continued to study graduate courses there for two years under the supervision of Wang Zhuxi, working on statistical mechanics.

His departure for the United States was delayed for one year, during which time he taught in a middle school as a teacher and studied field theory.

In 1949 he was invited to do his research at the Institute for Advanced Study in Princeton, New Jersey, where he began a period of fruitful collaboration with Tsung-Dao Lee.

After retiring from Stony Brook, he returned as an honorary director of Tsinghua University, Beijing, where he is the Huang Jibei-Lu Kaiqun Professor at the Center for Advanced Study (CASTU).

In January 2005, Yang married Weng Fan (Chinese: 翁帆; pinyin: Wēng Fān, a university student.

At the University of Chicago, Yang first spent twenty months working in an accelerator lab, but he later found he was not as good as an experimentalist and switched back to theory.

Yang, who has demonstrated on a number of occasions his generosity to physicists beginning their careers, told me about his idea of generalizing gauge invariance and we discussed it at some length...I was able to contribute something to the discussions, especially with regard to the quantization procedures, and to a small degree in working out the formalism; however, the key ideas were Yang's.

Lee proposed that in the weak interaction the parity symmetry was not conserved, Chien-shiung Wu's team at the National Bureau of Standards in Washington experimentally verified the theory.

In the 1970s Yang worked on the topological properties of gauge theory, collaborating with Wu Tai-Tsun to elucidate the Wu–Yang monopole.

He studied the theory of phase transition and elucidated the Lee–Yang circle theorem, properties of quantum boson liquid, two dimensional Ising model, flux quantization in superconductors (with N. Byers, 1961), and proposed the concept of Off-Diagonal Long-Range Order (ODLRO, 1962).