Abstract:Onsager inspired Yang Chen Ning to calculate spontaneous magnetization of the Ising model, prove unit circle theorem, define the?? concept of off-diagonal long-range order, and propose the Yang-Baxter equation. The example of Onsager’s academic influence on Yang shows two points. First, as long as research topics are related to basic phenomena or disciplinary, small research topics may lead to a series of problems, which further led to great progress and even revolutionary breakthrough. Secondly, to find good research topics need deep insight, and deep sight is inseparable from theoretical accumulation and practice. Theoretical accumulation implies deep theoretical foundation and liberal theoretical vision. Calculation and reduction is essential practice to theoretical discipline.