It was then classified as a National Type Secondary School after the enforcement of the Malaysian Education Act 1957.
It was first located beside Jalan Woo Saik Hong in the town area.
As San Min High School is a Chinese secondary school (SMJK), Chinese language (Bahasa Cina) is a compulsory subject to be taken during Sijil Pelajaran Malaysia (SPM) for all students with Chinese primary school background (SJKC).
The Name of the school is believed to have originated from Sun Yat-sen's Three Principles of the People (Chinese:三民主义).
Prior to moving to the current location, the school compound was small and was in a deplorable condition.