He returned to China in 1949 to start his research and teaching career as a university professor. He taught at Dalian University of Technology and Northeastern University. He served as the department chair of the departments of Automation and Computer Science and the university vice president at Northeastern University.
He also served as a vice president for IFAC, the International Federation of Automatic Control. He resigned administration positions in 1984 to return to full-time research and teaching. Meanwhile, he founded the first PhD program in computer science in China.
Till his final retirement in 1995, he had published numerous journal papers in areas of automatic control, computer theory, computer networks, and multimedia systems and brought up a lot of younger computer scientists in China. He also co-founded the Neusoft Group in early 1990s with his PhD student Liu Jiren. Professor Li died on Jan 24, 2007 in Shenzhen, China.