After receiving his Ph.D. from May 1st, he taught in California for many years, and was hired as a visiting professor by Hong Kong University of Science and Technology in the early 1990s. 1993, when Xiang Wuyi was teaching in Hong Kong, he solved a math problem that no one in the world could prove for 380 years. This geometric theorem, which has puzzled scientists for 380 years, is about' astronomer John Képler stated a theorem in 16 1 1, which involves the most effective way to put a round object into a rectangular box. For example, the best way to pile oranges in a cardboard box is to put another orange in the hollow formed by every three oranges in the lower layer. But for centuries, mathematicians have spent countless efforts, but they can't prove the truth of Képler's theorem. I spent 15 months with Professor Wuyi, during which his work faded from the United States to Hong Kong, but his determination to overcome this math problem never wavered. After more than a year of painstaking research and reasoning, Xiang Wuyi wrote a proof with a thickness of 150 pages, which proved that Képler's theorem was correct.

At that time, Ian Stuart, a mathematician at the University of Warwick in the United States, once said that if this certificate could pass the rigorous examination, Item May Day would make a jaw-dropping achievement in the whole history of mathematics. Chen Shengshen, a mathematician in China, also said that it is a very arduous task to prove May Day with many original ideas. Facts have proved that the proof of item 51 can stand up to strict examination.

At that time, newspapers and periodicals in China, such as Reference News and Kingdom of Mathematics, reported on the topic "Chinese-American professors solved the mystery of Zhan Lao's geometric theorem to May Day".

Over the years, Xiang Wuyi often went to Tsinghua University, Peking University and other famous universities for lectures, exchanges and academic research as a visiting scholar in the United States, and also specially compiled a textbook "Calculus Outline" for mathematics teaching in domestic universities.