Semiconductor spintronics is an important research area in condensed matter physics,as understanding spin dynamics in semiconductors is vital for the advancement of novel spintronic de-vices.Time-resolved magneto-optical Faraday and Kerr rotation spectroscopy are the key experimental methods to study these dynamics,which has been extensively applied to investigate spin polarization and spin relaxation in various semiconductors.This article provided an introduction on the fundamen-tal principles of time-resolved magneto-optical Faraday and Kerr rotation spectroscopy and highlighted a few significant studies in both well-known and novel semiconductors.The aim was to inspire students'interest in semiconductor spintronics and ultrafast spin dynamics,and to encourage further exploration in this exciting field.