His research focuses on transportation systems, environment (especially air quality), energy, and sustainable development. Gao received his degrees from the University of California at Davis in 2004 (Ph.D. in CEE, M.S. in Statistics, and M.S. in Agriculture and Resource Economics). Gao offers a graduate course CEE6650 on environment/energy and transportation systems. He also teaches SYSEN5300: Systems Engineering and Six-Sigma for the Design and Operation of Reliable Systems.