Hai-Lung Dai was born in Taiwan and attended the National Taiwan University. He graduated in 1974 with his undergraduate degree. After two years of military service, he began his Ph.D. work at the University of California Berkeley. He worked for a short time at MIT, and then accepted a position at the University of Pennsylvania in 1984. He became a full professor there in 1992 and served as Hirschmann-Makineni Chair from 2002-2007. During his time at the University, he created the Penn Science Teacher Institute, which helped to train high and middle school science teachers over 10 years.

In 2007, he became Dean of the College of Science and Technology at Temple University. There, he served as Provost of the University from 2013-2016. He is currently Kaura H. Carnell Professor of Chemistry there. His work at Temple University has transformed the program into a leading scientific player.

Throughout his career, he has won many awards. They included the Coblentz Award in Spectroscopy, the Alexander von Humboldt Award for Senior US Scientists, the Ellis R. Lippincott from OSA, the Michael P. Maole International Leadership Award, and the Langmuir Lectureship Award from the American Chemical Society.