Harm Jan Smid was born in Leiden (Leyden), The Netherlands. He received his primary and secondary education at schools in Leiden. In 1963 he started to study mathematics and physics at the Leiden University. He earned his bachelor degree in 1968, his master degree in 1973.

He began teaching mathematics at a school for secondary education in Leiden in 1966. In 1975, he was appointed as lecturer in mathematics and mathematics education at a teacher training College in Delft. In 1981, he became assistant professor, later associate professor, in mathematics and mathematics education at the Delft University of Technology. At first he was engaged in research in the achievements of foreign students in Delft and in Computer Assisted Learning. Later, his focus was on the history of mathematics education. He earned his PhD in 1997 with a thesis on the history of Dutch mathematics education in the first half of the 19^thcentury. After his retirement in 2007, he remained active in this field. In 2008, he was awarded with a prize by the Leiden Historical Society for his article on M.I.S. Bevel, a mathematics teacher in Leiden in the first decades of the 19^thcentury. He also wrote the jubilee book on the occasion of the 90^thbirthday of the Dutch Association of Teachers of Mathematics in 2015. In total, his publication list counts more than 90 items.